UNIVERSITY  OF  CALIFORNIA 

ANDREW 

SMITH 

HALLIDIL: 


^  »• 


PREFACE 


"  THE  printed  matter  here  presented  is  designed  to  serve  as  an  aid 
in  connection  with  the  lectures  on  machine-shop  methods  given  in  the 
Mechanical  Department  at  the  Michigan  Agricultural  College.  There 
are  many  questions  connected  with  machine-shop  practice  which  can, 
be  more  systematically  and  economically  treated  in  the  class-room 
than  by  giving  individual  instruction  in  the  shop.  Some  of  these  ques- 
tions will  be  treated  in  these  notes,  and  they  will  be  further  discussed 
and  elaborated  before  the  class.  The  expressions  exhibited  and  black- 
board sketch,  used  in  the  side-headings,  mean  that  the  apparatus  to 
which  the  text  refers  is  shown  before  the  class  or  illustrated  on  the 
blackboard.  At  the  discretion  of  the  instructor  the  student  will  be 
required  to  sketch  the  apparatus  exhibited;  however,  the  work  is 
largely  illustrated  by  detached  blue-print  sketches  and  printed  plates, 
to  which  the  text  refers  by  number.  Additional  matter  will  be  given 
in  the  class-room,  and  it  is  intended  that  the  examinations  shall,  as 
far  as  practicable,  cover  the  whole  subject." 

The  foregoing  brief  introduction,  which  was  printed  in  the  two 
preceding  loose-leaf  editions  of  this  work,  is  reproduced  here  to  indi- 
cate the  circumstances  under  which  the  work  has  been  developed  and 
its  primary  object.  In  its  original  form  the  book  served  its  purpose 
well  at  the  college  mentioned  above,  and  the  enlarged  edition  is  pre- 
sented with  the  hope  that  it  may  be  equally  valuable  in  connection 
with  the  engineering  departments  of  other  schools. 

In  the  foot-notes  there  are  a  few  references  to  articles  in  such  tech- 
nical journals  as  are  likely  to  be  found  in  college  libraries.  It  may  be 
advantageous,  in  connection  with  a  course  of  lectures,  to  require  some 
of  the  students  to  read  these  or  other  similar  articles  and  report  their 
findings  to  the  class  for  discussion.  Such  variations  from  a  fixed 
method  serve  to  keep  up  the  interest  of  the  student  and  at  the  same 
time  tend  to  broaden  his  views.  In  institutions  which  have  no  regular 


139702 


iv  PREFACE 

course  of  lectures  on  shop-practice,  the  book  may  prove  of  value  for 
reference  in  connection  with  machine-shop  instruction. 

In  some  of  the  larger  shops  of  this  country  there  has  recently  been 
introduced  a  system  which  requires  that  the  workman  shall  follow  a 
carefully  prepared  order  of  operations  in  his  work.  As  suggestive  of 
what  may  be  done  in  this  direction,  the  instructions  for  some  of  the 
exercises  in  Chapters  XVII  and  XVIII  are  presented  in  this  regular 
order. 

The  list  of  questions  at  the  end  of  the  book  is  not  a  complete  outline 
of  the  contents,  but  it  may  be  supplemented  by  additional  questions 
at  the  discretion  of  the  instructor.  Such  an  outline  is  of  value  to  the 
student  in  preparing  for  examinations. 

It  is  hoped  that  a  considerable  portion  of  the  book  may  be  found 
profitable  reading  for  experienced  machinists.  This  class  of  readers, 
bearing  in  mind  that  many  of  the  students  for  whom  the  work  is  prin- 
cipally designed  know  practically  nothing  of  machine-shop  practice, 
will  overlook  the  elementary  character  of  much  of  the  text. 

Among  the  publications  consulted  in  the  preparation  of  the  manu- 
script may  be  mentioned  "Modern  Machine-shop  Practice/'  by  Joshua 
Rose;  "Modern  Machine-shop  Tools,"  by  Vandervoort;  and  "Practical 
Treatise  on  Gearing/'  and  other  publications  by  The  Brown  and  Sharpe 
Manufacturing  Company.  Frequent  reference  was  also  made  to  the 
files  of  "The  American  Machinist  "  and  "Machinery." 

A  considerable  number  of  the  cuts  which  illustrate  the  text  were 
made  expressly  for  this  work;  many  others  were  loaned  by  manufac- 
turers. Grateful  acknowledgment  is  here  made  to  the  friends  who  have 
thus  assisted  us.  It  is  due  to  the  manufacturers  to  explain  that  the 
cuts  used  do  not  in  every  instance  represent  their  best  work.  In  a  few 
cases  the  simpler  machines  were  chosen  in  preference  to  the  more  elab- 
orate designs,  in  order  to  illustrate  a  principle  more  clearly.  Acknowl- 
edgments are  due  also  to  the  publishers  of  the  "American  Machinist," 
who  very  kindly  presented  a  number  of  valuable  electrotypes.  During 
the  preparation  of  the  manuscript  the  author  was  afflicted  with  a  serious 
and  persistent  eye  strain.  Sincere  thanks  are  tendered  Mr.  C.  E. 
Johnson,  of  the  class  of  1905,  who  in  this  emergency  rendered  valuable 
assistance  in  connection  with  the  drawings. 

W.  S.  L. 

AGRICULTURAL  COLLEGE,  MICHIGAN. 


MACHINE-SHOP    TOOLS 
AND    METHODS 


BY 


W.    S.    LEONARD 

Instructor  in  Machine-shop  Practice  and  in  Practical  Machine  Design 
Michigan  Agricultural  College 


itt)  nearlji  700  Illustrations 


THIRD  EDITION,  REVISED  AND  ENLARGED 
FIRST   THOUSAND 


NEW  YORK 

JOHN"   WILEY   &  SONS 
LONDON  :   CHAPMAN  &  HALL,  LIMITED 
1905 


Engineering 
Library 


Copyright,  1905, 

BY 

W.   S.   LEONARD. 


IOBERT    DRrMMOXD,    PRINTER,    NEW   YORK. 


CONTENTS 


CHAPTER  I 

PAGES 

THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP.     STANDARDS  OF  LENGTH.         1-29 


CHAPTER  II 
THE  HAMMER  AND  ITS  USE 30-36 

CHAPTER  III 
CHISELS  :    THEIR  FORMS  AND  USES 37-43 

CHAPTER  IV 
FILES  AND  FILING 44-59 

CHAPTER  V 
THE   SURFACE-PLATE   AND  SCRAPER 60-67 

CHAPTER^  VI 
THE  VISE  AND  SOME  VISE  ACCESSORIES 68-73 

CHAPTER  VII 
DRILLING-MACHINES 74-111 

CHAPTER  VIII 
DRILLS  AND  DRILLING 112-124 

CHAPTER  IX 

DRILL-SOCKETS,  DRILL-CHUCKS,  AND  ACCESSORIES 125-131 

v 


vi  CONTENTS 

CHAPTER  X 

PAGES 

CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS 132-144 

CHAPTER  XI 
LATHES 145-177 

CHAPTER  XII 
TURRET-MACHINES  AND  TURRET-MACHINE  WORK 178-207 

CHAPTER  XIII  . 
LATHE-  AND  PLANER-TOOLS 208-223 

CHAPTER  XIV 
LATHE-CENTERS,  WORK-CENTERS,  ETC 224-232 

CHAPTER  XV 
METHODS  OP  DRIVING  WORK  IN  THE  LATHE.     DOGS  AND  CHUCKS 233-245 

CHAPTER  XVI 
LATHE-ARBORS,  OR  MANDRELS,  AND  ARBOR-PRESSES 246-253 

CHAPTER  XVII 
SOME  EXAMPLES  OP  ENGINE-LATHE  WORK 254-277 

CHAPTER  XVIII 
THREAD-CUTTING  IN  THE  ENGINE-LATHE 278-293 

CHAPTER  XIX 
SCREW-THREADS,  TAPS,  AND  DIES.    BOLT-  AND  NUT-THREADING  MACHINES  .   294-313 

CHAPTER  XX 
THE  BORING-BAR  AND  ITS  USE 314-327 

CHAPTER  XXI 

HORIZONTAL  BORING-  AND  DRILLING-MACHINES  AND  WORK.    CRANK-BORING 

MACHINE 328-341 

CHAPTER  XXII 
VERTICAL  BORING-  AND  TURNING-MILLS,  TOOLS  AND  WORK 342-355 


CONTENTS  vii 

CHAPTER  XXIII 

PAGES 

PLANERS  AND  SHAPERS  AND  PLANER  AND  SHAPER  WORK 356-387 

CHATTER  XXIV 
SLOTTING-MACHINES  AND  THE  WORK  TO  WHICH  THEY  ARE  ADAPTED  . . .  388-393 

CHAPTER  XXV 
KEY-SEATING  MACHINES  AND  KEYS 394-396 

CHAPTER  XXVI 
MILLING-MACHINES  AND  MILLING-MACHINE  WORK  .  , 397-454 

CHAPTER  XXVII 
SPECIAL  GEAR-MACHINES 455-466 

CHAPTER  XXVIII 
GRINDING-MACHINES  AND  METHODS 467-491 

CHAPTER  XXIX 
POLISHING-  AND  BUFFING-WHEELS 492-495 

CHAPTER  XXX 
THE  INTERCHANGEABLE  SYSTEM  OF  MANUFACTURING 496-505 

CHAPTER  XXXI 
MISCELLANEOUS  MACHINE-SHOP  METHODS 506-512 

CHAPTER   XXXII 
TABLES,  RECIPES,  ETC 513-520 

APPENDIX 

QUESTIONS  ON  THE  TEXT 521-534 

INDEX.  .  535-554 


MACHINE-SHOP  TOOLS  AND   METHODS 


CHAPTER  I 

\ 

THE    MEASURING  SYSTEM  OF  THE  MACHINE-SHOP—STANDARDS  OF 

LENGTH 

The  British  Yard. — A  vast  deal  of  time  and  energy  have  been  expended 
by  the  nations  of  civilization  in  an  endeavor  to  arrive  at  scientific  stan- 
dards of  money.  The  agitations  of  this  question  in  the  United  States  at 
various  times,  and  especially  during  the  closing  years  of  the  nineteenth 
century,  indicate  the  importance  with  which  the  subject  is  viewed  in  this 
country.  Of  scarcely  less  importance  is  a  standard  of  length  in  the 
mechanical  world;  and  much  labor  and  research  have  been  directed 
towards  establishing  standards  of  length  upon  scientific  bases.  The 
final  outcome  of  these  efforts,  so  far  as  the  English-speaking  peoples 
are  concerned,  was  the  British  Imperial  yard.  The  yard  became  the  unit 
of  length  in  England  by  legal  enactment  in  1824,  but  the  metallic  repre- 
sentation of  this  unit  was  destroyed  by  fire  in  1834.  Later  a  more  accu- 
rate standard  was  made,  and  to  provide  against  its  being  lost  a  number 
of  duplicates  were  made  and  deposited  with  other  countries.  This 
later  standard  was  recognized  by  an  Act  of  Parliament  in  1855,  and 
a  copy  of  it  was  presented  to  the  United  States  in  1856. 

This  " yardstick"  is  made  of  " Bailey's  metal,"  a  composition 
chosen  after  much  experimentation.  The  bar  is  38"  long  by  1"  square, 
and  lines  36"  apart  are  marked  upon  gold  studs  sunk  to  its  neutral 
axis.  The  studs  are  thus  placed  as  a  provision  against  flexure.  To 
further  provide  against  errors  from  this  cause  the  positions  of  support- 
ing the  bar  had  been  determined  by  elaborate  calculations  before  the 
lines  were  drawn.  As*  all  metals  change  in  dimensions  with  variations 
in  temperature,  the  British  yard  was  established  as  standard  at  a  tem- 
perature of  62°  F. 


2  MACHINE-SHOP  TOOLS  AND   METHODS 

After  having  been  made  with  the  greatest  precision  possible  the 
"yardstick"  presented  to  the  United  States  was  found  to  be  .000088" 
short  at  62°  F.  This,  however,  did  not  necessitate  any  alteration  in 
the  bar,  but  merely  suggested  changing  the  temperature  of  the  room 
in  which  it  was  kept.  At  62.25°  the  bar  is  so  nearly  a  duplicate  of  the 
original  that  no  difference  can  be  discovered  with  the  most  costly  and 
elaborate  instruments. 

The  French  Standard. — In  their  efforts  to  discover  some  natural 
standard  the  French  settled  upon  the  ten-millionth  part  of  a  quadrant 
of  the  earth  through  Paris.  This  unit  they  called  the  metre  and  it  is 
equivalent  to  39.37  English  inches.  To  be  independent  of  any  instru- 
ment for  gaging  the  temperature  the  French  made  the  metre  standard 
at  the  temperature  of  melting  ice,  or  32°  F.  While  the  English  sys- 
tem predominates  in  America,  the  metric  system  is  used  to  a  consider- 
able extent,  and  it  is  generally  preferred  in  scientific  investigations.* 

The  manufacturers  of  the  measuring  instruments  sold  to  the  pub- 
lic use  as  their  guides  duplicates  of  tVie  authorized  standard.  The 
making  of  these  duplicates,  as  well  as  the  production  of  the  original, 
involves  very  great  refinements.  For  instance,  the  temperature  of  ths 
metallic  bar  being  lower  than  that  of  the  human  body,  special  precau- 
tions have  to  be  taken  when  comparisons  are  made  with  duplicate  stan- 
dards. Otherwise  the  heat  of  the  body  would  expand  the  yardstick. 

The  high  degree  of  refinement  referred  to  above  is,  of  course,  unneces- 
sary in  average  shop  work,  and  is  commercially  impossible  in  all  but  ex- 
ceptional cases.  Nevertheless  the  degree  of  accuracy  required  in  every- 
day practice  is  such  as  to  justify  the  great  expense  of  establishing  and 
maintaining  an  invariable  standard.  The  necessity  for  this  invariable 
standard  may  be  illustrated  as  follows:  Suppose  John  Jones  in  Chicago 
sends  to  Brown  in  New  York  for  a  gear  to  fit  a  2"  shaft.  Now  two 
inches  in  New  York  must  agree  within  about  .001"  with  two  inches 
in  Chicago  or  the  gear  will  not  fit.  Both  must  be  Vis  of  the  standard 
yard,  and  both  Jones  and  Brown  must  have  means  for  determining 
the  two  inches  with  practical  accuracy.  In  this  connection  we  shall 
describe  in  detail  the  measuring-instruments  of  the  machine-shop. 

*  In  1893  the  standard  yardstick  was  superseded  in  the  National  Bureau  of 
Standards  by  the  National  Prototype  Metre,  Congress  having  in  1866  legalized  the 
metric  system  and  defined  the  yard  as  380%w  metre.  However,  this  action  is  not 
likely  to  change  the  prevailing  usage  of  the  people. 

A  very  interesting  account  of  the  National  Prototype  Meter  is  published  by  The 
National  Bureau  of  Standards. 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  3 

Rules,  Wood  and  Steel. — The  common  boxwood  rule  is  familiar  to 
all,  but  in  the  machine-shop  this  rule  is  used  for  only  very  general  and 
rough  measurements,  the  steel  rule  or  scale  being  used  for  finer  work. 
The  boxwood  rule  is  less  accurate  than  the  steel  rule  partly  because 
it  is  made  with  joints  subject  to  wear,  and  also  for  reasons  of  minor  im- 
portance. The  steel  rule~is  made  without  any  joint,  and,  while  subject 
to  some  variation  due  to  temperature  changes,  the  material  measured 
is  affected  in  very  nearly  the  same  ratio,  and  when  made  by  a  reliable 
manufacturer  the  steel  rule  is  a  fairly  accurate  tool.  It  requires  some 
skill,  however,  to  measure  to,  say,  within  .002"  by  a  rule  of  any  kind,  and, 
as  above  indicated,  the  fit  of  many  machine  details  is  required  to  be 
well  within  this  limit.  But  for  ordinary  measurements,  where  the 
parts  are  not  required  to  fit  as  a  gear  should  fit  its  shaft,  the  steel  rule 
is  satisfactory.  These  rules  are  made  in  various  graduations,  widths, 
lengths,  and  shapes.  Fig.  1  shows  a  common  form.  Figs.  2  and  3 


FIG.  1. 


FIG.  2. 


FIG.  3. 

show  respectively  a  square  rule  and  a  triangular  rule.  The  hook  rule 
shown  in  Fig.  4  is  a  very  convenient  tool.  In  setting  inside  calipers 
by  it  one  point  of  the  caliper  is  held  against  the  hook,  while  the  other 
point  is  adjusted  to  the  required  dimension.  This  rule  is  advantageous, 
also,  in  measuring  the  distance  from  a  recess  in  the  hub  of  a  pulley, 
for  instance,  to  the  end  of  the  hub,  and  in  many  other  ways.  The 
hook  may  be  detached  from  the  rule  by  turning  the  eccentric  screw 
one-half  revolution. 

Common  Machinists'  Calipers. — In  fitting  one  piece  to  another,  and 
also  for  transferring  dimensions  from  the  steel  rule,  common  calipers 


MACHINE-SHOP  TOOLS  AND  METHODS 


are  frequently  used.  They  are  made  in  two  leading  designs,  friction- 
joint  and  spring-joint.  These  again  have  various  modifications,  but 
the  modifications  are  not  of  sufficient  importance  to  justify  a  detailed 
description  within  the  scope  of  this  work.  Fig.  5  shows  an  outside 
spring-joint  caliper.  It  is  used  generally  for  outside  dimensions,  and 
especially  for  calipering  the  diameters  of  cylinders.  Fig.  6  is  an  inside 


FIG.  4. 


5. 


FIG.  6. 


caliper  of  the  same  design  as  Fig.  5.  Its  principal  use  is  that  of  caliper- 
ing internal  diameters,  but  it  may  also  be  used  for  rectangular  and 
other  shaped  openings.  These  calipers  are  often  made  with  "  solid " 
nuts,  but  the  designs  here  shown  have  spring-nuts.  Slight  pressure 
on  the  knurled  end  of  the  nut  causes  disengagement  of  the  thread  in 
\  the  nut,  when  it  may  be  quickly  moved  along  the  screw,  allowing  the 
caliper  to  open  or  close  in  an  instant. 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  5 

The  calipers  shown  in  Figs.  7  and  8  are  good  examples  of  the  friction 
or  firm-joint  pattern.  Spring-joint  calipers  are  adjusted  by  screw  and 
nut,  but  the  old  style  firm-joint  calipers  are  adjusted  by  repeated  light 
taps  of  the  caliper  limb  against  t  some  convenient  object — preferably  a 
block  of  wood.  This  may  appeaj  to  be  a  very  awkward  method; 
nevertheless  some  good  mechanics  prefer  these  calipers  to  the  spring- 
joint  design. 

The  instrument  shown  in  Fig.  9  is  known  as  a  double  caliper.  In 
reality  it  combines  in  one  tool  an  inside  caliper,  an  hermaphrodite,  and 


FIG.  7. 


FIG.  9. 


dividers.  The  double  joints  admit  of  the  caliper  being  used  with  advan- 
tage in  boring-bar  work.  By  adjusting  the  joints  so  as  to  bring  the 
legs  parallel  the  points  of  the  caliper  will  enter  a  narrow  space  between 
a  boring-bar  and  hole  which  could  not  be  reached  by  the  single-joint 
caliper.  This  will  often  save  the  trouble  of  taking  the  boring-bar  out 
to  caliper  the  hole. 

Universal  Dividers. — A  very  unique  and  handy  tool  is  illustrated 
in  Figs.  10  and  11.  The  manufacturers  call  this  instrument  "universal 
dividers."  By  inclining  the  adjustable  point  inward  as  shown,  very 
small  circles  may  be  drawn.  When  reversed  the  point  will  work  closer 
to  shoulders,  and  draw  larger  circles  than  is  possible  with  other  dividers 
of  this  character  which  have  straight  points.  Any  one  of  the  points 


6 


MACHINE-SHOP  TOOLS  AND  METHODS 


B,  C,  D,  or  V  may  be  inserted  in  place  of  either  of  the  points  shown 
in  the  instrument.  B  is  a  needle-point,  C  a  pen-point  attachment,  D 
an  extra  straight  point  and  socket,  and  V  a  center  point  designed  as  a 
guide  when  drawing  circles  concentric  with  a  reamed  center  in  the  end 
of  a  shaft.  A  pencil-point  may  also  be  used  in  one  of  the  sockets.  An 


D 


FIG.  10. 


FIG.  11. 


auxiliary  beam  long  enough  for  drawing  25"  circles  is  furnished  with 
the  instrument. 

Hermaphrodite  Caliper. — The  tool  shown  in  Fig.  12  is  commonly 
known  as  the  hermaphrodite  caliper — a  very  awkward  name.  In  spite 
of  its  name  this  is  quite  a  useful  instrument.  It  is  used  in  the  same 
way  that  a  carpenter  uses  a  marking-gage  when  drawing  lines  parallel 
with  the  edges  of  rectangular  objects.  It  can  be  used  also  to  draw 
concentric  arcs  on  the  end  of  a  cylinder  or  circular  disk.  In  drawing 
these  arcs  the  legs  of  the  caliper  should  be  held  in  radial  lines,  the  caliper- 
point  being  pressed  against  and  moved  around  the  periphery  of  the 
circle. 

Thread-calipers. — The  calipers  shown  in  Figs.  13, 14  and  15  are  called 
respectively  thread-calipers,  outside-thread  calipers,  and  inside-thread 
calipers.  The  points  of  Fig.  13  are  made  quite  broad  to  give  a  more 
reliable  contact  on  V  and  U.  S.  standard  threads.  In  order  to  measure 
the  small  diameter  at  the  root  of  a  screw-thread  the  points  of  Fig.  14 
are  made  thin.  Fig.  15  is  designed  to  measure  the  greater  diameter 
of  internal  thread.  A  screw-thread  is  more  difficult  to  measure  accu- 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  7 


FIG.  12. 


FIG.  13. 


FIG.  14. 


FIG.  15. 


8  MACHINE-SHOP  TOOLS  AND  METHODS 

rately  than  a  plain  cylinder,  and  these  tools  are  not  reliable  for  close- 
fitting  screws.  They  answer  well  enough  for  approximate  measure- 
ments, but  one  of  the  tools  mentioned  later  should  be  used  for  more 
exacting  requirements.  Otherwise  the  screw  itself  applied  directly 
in  the  threaded  hole  must  be  the  final  test. 

Setting  Calipers. — To  make  an  accurate  measurement  with  the  in- 
side caliper,  hold  one  leg  against  the  inside  of  the  hole  and  adjust  and 
vibrate  the  other  leg  until  its  point  just  touches  the  part  of  the  hole 
diametrically  opposite.  To  transfer  the  measurement  from  the  inside 
caliper  to  the  outside,  place  the  extreme  point  of  one  leg  of  the  out- 
side caliper  in  contact  with  the  similar  point  of  the  inside  caliper,  and 
vibrate  and  adjust  the  other  leg  of  the  outside  caliper  until  its  extreme 
point  just  touches  the  other  extreme  point  of  the  inside  caliper.  Great 
care  must  be  taken  to  find  these  extreme  points,  and  the  caliper  must 
not  be  forced  over  in  the  least  degree.  Forcing  the  caliper  over 
another  caliper,  or  over  a  shaft,  will  cause  it  to  register  falsely  and  lead 
to  misfits. 

The  Vernier  Caliper. — The  Vernier  caliper  is  a  measuring-instru- 
ment much  used  in  tool-making  and  other  fine  work.  It  takes  its 
name  from  Pierre  Vernier,  who  invented  the  method  of  graduating 
which  admits  of  reading  by  the  unaided  eye  dimensions  which  could 
not  thus  be  read  from  a  common  rule.  The  instrument  is  based  on 
the  principle  that  the  eye  can  discover  when  two  lines  are  coincident, 
but  cannot  determine  their  distance  apart  when  they  are  not  coinci- 
dent. Fig.  16  shows  a  small  pocket  Vernier  caliper.  It  is  designed 


FIG.  16. 


for  both  outside  and  inside  measurements,  the  outside  measurements 

being  taken  between  the  jaws  at  0,  and  the  inside  over  the  jaws  at  7. 

There  are  two  leading   systems  of   graduation   used   on   machine- 


THE  MEASURING   SYSTEM  OF  THE  MACHINE-SHOP 

shop  Vernier  calipers.  The  scale  S  of  the  caliper  shown  in  the  figure 
is  divided  into  l/&o",  1/io",  l/2",  etc.,  the  smallest  divisions  being  equal 
to  .020".  Twenty  divisions  on  the  vernier  V  equal  nineteen  of  the 
smallest  divisions  on  the  scale.  The  difference  between  a  division  on 
the  vernier  and  one  on  the  scale  (smallest  divisions  being  meant  in 
both  cases)  is,  therefore- for  this" instrument  1/2oX1/50  (or  .05X.02) 
=  .001".  On  the  other  caliper  the  smallest  scale  divisions  equal  .025" 
or  l/4o",  and  twenty-five  divisions  on  the  vernier  equal  twenty-four 
on  the  scale,  the  difference  being  l/2B^/4o  (or  .04 X. 025)  =  .001. 
Then  starting  at  zero  with  either  instrument,  moving  the  vernier  jaw 
until  its  second  line  coincides  with  the  second  line  on  the  scale  will  give 
.001"  opening;  moving  the  jaw  to  bring  its  third  line  coincident  with 
the  next  forward  line  on  the  scale  will  give  .002"  opening,  etc.  Thus, 
to  set  the  caliper  shown  in  the  figure: 

Divide  the  number  of  thousandths  of  an  inch  in  required  dimen- 
sion by  number  of  thousandths  in  smallest  division  of  the  scale  St 
both  values  being  expressed  as  whole  numbers.  Move  sliding  jaw 
until  its  zero-mark  points  off  the  number  of  divisions  on  the  scale  indi- 
cated by  the  whole  number  in  the  quotient.  Move  jaw  further  until 
the  line  of  the  vernier  corresponding  to  the  number  of  thousandths 
in  the  remainder  coincides  with  the  next  forward  line  on  the  scale.  The 
opening  at  0  will  be  as  required.  For  example,  let  it  be  required  to 
set  this  caliper  to  .137".  137-^-20  =  6  as  the  whole  number  in  the  quo- 
tient, with  17  as  the  remainder.  So  we  move  the  sliding  jaw  (vernier 
jaw)  a  distance  equal  to  six  divisions  on  the  scale  S,  and  then  move 
it  further  to  bring  its  seventeenth  division  in  line  with  the  next  for- 
ward division  on  the  scale.  If  the  required  dimension  be  divisible 
without  a  remainder  by  the  number  of  thousandths  in  the  smallest 
scale  division,  the  required  dimension  may  be  read  from  the  scale  as 
would  be  done  with  a  common  scale. 

Applying  the  same  rule  to  the  other  Vernier  caliper  and  using  the 
same  required  dimension  for  opening  of  jaws  we  have  137  -j-  25  =  5 
for  the  number  of  fortieths  to  be  read  from  the  scale,  and  12  as  the 
number  of  thousandths  to  be  measured  by  the  vernier. 

Micrometer-calipers. — This  instrument,  the  typical  form  of  which 
is  shown  in  Fig.  17,  is  perhaps  more  generally  used  than  the  Vernier 
caliper.  It  consists  of  the  U-shaped  frame  A,  the  anvil  B,  spindle  C, 
sleeve  D,  and  thimble  E.  The  spindle  is  threaded  on  the  concealed 
end  and  screws  through  a  fixed  nut  in  the  frame.  In  setting  the  instru- 
ment the  thimble  E  is  turned  by  the  fingers,  carrying  the  screw  and 


10  MACHINE-SHOP  TOOLS  AND  METHODS 

spindle  with  it.  The  thread  on  the  screw  is  1/40"  =  .025//  lead.  There- 
fore one  revolution  of  the  thimble  advances  the  spindle  .025",  which 
is  equal  to  the  smallest  division  on  the  sleeve  D.  The  beveled  edge 
of  E  is  graduated  into  twenty-five  divisions.  If  then  E  be  turned  one 
division,  the  spindle  will  advance  1/4oX1/25=-001".  Thus  to  deter- 
mine the  opening  between  B  and  C,  read  the  graduations  on  the  sleeve 
D  as  of  a  common  rule,  observing  that  each  numbered  division  equals 
.100",  which  corresponds  to  four  revolutions  of  the  thimble.  Add  to 
the  value  thus  found  as  many  thousandths  of  an  inch  as  there  are  divi- 
sions on  the  thimble  between  its  zero  and  the  longitudinal  line  on  the 
sleeve.  The  sum  gives  the  opening,  which  on  the  instrument  of 'the 
illustration  is  .178".  Some  mechanics,  when  confused  as  to  the  read- 


A-FRAME 

B-ANVIL 

C-SPINDLF. 

D-SLEEVE 

E-THIMBLE 


FIG.  17. 

ing,  screw  the  spindle  against  the  anvil  and  then  unscrew  it  again, 
noting  the  number  of  turns.  Multiplying  the  number  of  turns  by  .025 
and  adding  the  thousandths  indicated  on  the  thimble  gives  the  opening. 

When  the  zero  of  the  thimble  does  not-  correspond  to  the  zero- 
line  of  the  sleeve  the  correction  may  be  made  (in  most  micrometers) 
by  a  small  screw  at  the  outer  end  of  the  anvil. 

Vernier  Graduation  on  Micrometers. — When  a  micrometer-caliper 
has  vernier  graduations  these  are  placed  on  the  sleeve  and  read  in  con- 
nection with  the  .001"  divisions  on  the  thimble.  Fig.  18  shows  one 
of  these  instruments.  Ten  of  the  vernier  divisions  or  spaces  at  D  equal 
nine  on  the  thimble  E.  The  thimble  spaces  being  .001",  the  difference 
equals  1/ioX1/iooo  =  1/ioooo  or  .0001".  The  principle  is,  of  course, 
the  same  as  explained  in  connection  with  Fig.  16,  but  the  finest  read- 
ings are  in  ten-thousandths,  while  the  Vernier  caliper  of  Fig.  16  reads 
no  finer  than  thousandths. 

Large  Micrometer-calipers. — Makers  of  micrometers  furnish  these 
instruments  with  various  modifications  and  minor  improvements. 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  11 

One  design  is  somewhat  similar  to  the  Vernier  caliper  of  Fig.  16;  but 
instead  of  the  vernier  it  has  a  micrometer-screw  arrangement  in  the 
end  of  the  sliding  jaw.  The  screw-thread  is  cut  but  little  longer  than 
one  inch  (as  is  the  case  with  most  micrometers),  but  the  sliding  jaw 

D 


FIG.  18. 


can  be  locked  at  intervals  of  one  inch  up  to  six  inches  from  the  fixed 
jaw.  Micrometers  of  the  U-shaped  pattern  have  been  made  with  a 
measuring  capacity  of  twelve  inches.  Sweet's  measuring-machine, 
Fig.  19,  is  a  good  example  of  a  large  micrometer.  Instead  of  having 


FIG.  19. 

l/4o"  lead,  the  screw  in  this  instrument  has  either  Vio"  or  l/2o"  lead. 
As  the  range  of  the  screw  is  but  one  inch,  test-rods  are  furnished  for 
the  zero  positions  when  measuring  greater  dimensions.  To  guard 
against  errors  that  might  be  occasioned  by  handling  these  rods  (which 
errors  would  be  caused  by  the  temperature  of  the  hand),  the  rods  are 
covered  with  rubber  sleeves.  This  provision  emphasizes  the  precau- 
tions necessary  in  very  fine  measurements. 


12 


MACHINE-SHOP  TOOLS  AND  METHODS 


Methods  of  Compensating  for  Errors  in  Screws. — There  is  considerable 
difficulty  in  making  screws  sufficiently  accurate  for  measuring-instru- 
ments. This  difficulty  is  due  in  part  to  commercial  considerations — 
the  price  must  not  be  prohibitive.  A  method  of  compensating  for 
minute  errors  in  screws  is  illustrated  in  Fig.  20.  Referring  to  this 
figure,  which  shows  an  instrument  of  the  same  design  as  that  represented 
in  Fig.  17,  E  is  the  thimble,  D  the  sleeve,  C  the  spindle,  and  B  the  anvil. 
As  the  thimble  revolves  in  the  direction  of  the  arrow  it  is  advanced 
by  the  concealed  screw  toward  the  zero-mark,  0.  Suppose  that  this 
screw  is  exactly  1/4o//  lead.  Then  will  the  zero-mark  on  the  beveled 


FIG.  20. 


edge  of  the  thimble  indicate  1/4o//  advance  for  each  revolution  or  for 
each  time  it  passes  a  line  P,  drawn  parallel  with  the  axis  of  the  thimble. 
If,  however,  the  lead  of  the  screw  be  slightly  greater  than  l/4o",  then 
it  will  require  less  than  one  revolution  to  advance  the  thimble  1/4o//..  and 
the  line  P  should  be  drawn  at  some  angle  with  the  axis  of  the  spindle,  as 
at  X.  This  line  X  may  be  marked  as  follows :  Starting  with  the  anvil  B 
and  spindle  C  in  contact,  both  B  and  C  being  assumed  to  have  flat 
ends,  establish  first  the  two  zero-marks  on  sleeve  and  thimble.  Now 
unscrew  C,  and  with  a  test-piece  1/4o"  long  resting  against  B,  screw  C 
.against  the  test-piece.  A  point  marked  on  the  sleeve  coincident  with 
the  zero-mark  of  the  thimble  will  lie  on  the  required  line.  In  a  similar 
manner,  and  with  other  test-pieces  varying  in  length  by  fortieths  of  an 
inch,  any  number  of  points  in  the  required  line  may  be  established.  A 
detachable  bar  graduated  and  set  to  the  required  angle  is  used  on  some 
instruments.  If  the  screw  of  the  instrument  be  of  irregular  lead,  the 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  13 

line  may  be  considerably  curved.  This  compensating  method  involves 
an  important  principle,  which  may  admit  of  other  applications  in  con- 
nection with  screws. 

This  process  of  establishing*  By  test-pieces  points  on  the  graduated 
line  of  a  micrometer  is  not  knowg,  by  the  writer  to  have  been  used,  but 
it  is  mentioned  for  the  instruction  of  the  student  as  a  possible  method. 
However,  the  angular  line  itself  is  known  to  have  been  used  for  correct- 
ing, or  compensating  for,  errors  in  screws. 

The  Pratt  and  Whitney  Measuring-machine. — We  have  already 
alluded  to  the  refinements  necessary  in  making  subdivisions  of  the 
standard  yard,  in  originating  standard  gages,  etc.  Fig.  21  shows  a 
machine  for  this  purpose.  An  adequate  description  of  this  machine 
is  impossible  within  the  space  here  available.  The  manufacturers  claim 
that  it  readily  indicates  variations  within  1/iooooo//.  This  is  about 
1/30o  the  thickness  of  common  newspaper.  The  largest  of  these  machines 
have  a  measuring  capacity  of  SO".  They  are  made  for  either  the  English 
or  the  metric  system  as  required. 

Screw-thread  Micrometer-caliper. — For  measuring  the  U.  S.  stand- 
ard and  V-shaped  screws  there  is  a  special  micrometer-caliper.  The 
measuring-points  of  this  instrument  are  of  special  construction,  as  shown 
in  Fig.  20,  the  movable  point  being  cone-shaped  and  the  fixed  point  V-- 
shaped. Thus  the  points  are  in  contact  on  the  angular  sides  of  the 
thread  rather  than  at  top  or  bottom,  and  the  dimension  registered  is 
the  pitch  diameter.  To  obtain  the  outside  diameter  we  add  to  the  pitch 
diameter  .6495"  divided  by  the  number  of  threads  per  inch  for  U.  S. 
standard,  and  .866"  divided  by  the  number  of  threads  per  inch  for  V 
thread. 

The  Inside  Micrometer-gage  shown  in  Fig.  22  was  designed  primarily 
for  internal  measurements,  but  it  may  be  used  as  an  end  gage,  for  setting 
calipers,  and  in  other  ways.  The  thimble  is  graduated  to  thousandths 
of  an  inch,  and  the  screw  has  a  movement  of  half  an  inch.  By  using 
the  extension  rods  shown  in  connection  with  the  instrument,  measure- 
ments may  be  made  in  thousandths  of  an  inch  from  3  to  6  inches. 

Fig.  23  shows  a  Micrometer  Depth  Gage. — The  measuring-rod  on 
this  instrument  has  little  V  grooves  exactly  half  an  inch  apart  (as  have 
also  the  extension-rods  shown  in  Fig.  22) ,  and  the  screw  has  a  movement 
of  half  an  inch.  By  an  ingenious  clamping  device  near  the  end  of  the 
thimble  the  rod  may  be  adjusted  and  clamped  at  intervals  of  half  an 
inch  from  zero  to  2l/2ff.  The  thimble  is  graduated  to  read  to  thousandths 
of  an  inch,  and  by  this  means,  in  connection  with  the  screw,  any  dimen- 


.'1~~      '  ^-;x 

vS s 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP 


15 


sions  between  the  notches  may  be  measured  in  thousandths  of  an  inch. 
This  instrument  is  used  in  measuring  the  depth  of  slots,  drilled  holes,  etc. 


Inside  Micrometer  Caliper 

FIG.  22. 


5482   IE 

1     1 

Mill: 

FIG.  23. 


FIG.  24. 


FIG.  25. 


Caliper-gages  (Figs.  24  and  25). — The  caliper-gage  is  a  non-adjust- 
able gage  for  standard  dimensions.  As  made  by  the  Brown  &  Sharpe 
Manufacturing  Company,  these  instruments  vary  in  sixteenths  of  an  inch 
from  Y/'  to  2",  and  above  2"  in  eighths  of  an  inch.  Being  made  in  the 


16 


MACHINE-SHOP  TOOLS  AND  METHODS 


caliper  form  they  are  as  well  adapted  for  measuring  rectangular  shapes  as 
for  cylindrical.  The  caliper-gage  should  not  be  applied  to  a  shaft  while 
the  shaft  is  turning;  for,  notwithstanding  it  is  made  quite  rigid,  it  is  likely 
to  be  sprung  out  of  shape  if  used  in  this  manner.  Obviously  it  may 
be  used  to  set  common  calipers  by,  as  well  as  for  direct  measurement. 
All  things  considered,  the  caliper-gage  is  the  best  standard  measuring- 
instrument  used  in  the  shop. 

Collar-  and  Plug-gages  (Figs.  26  and  27) .  —  Collar-  and  plug-gages 
are  cylindrical  in  form  and  are  preferred  by  some  mechanics  because 


FIG.  26. 


FIG.  27. 


of  their  greater  durability  and  because  they  are  more  reliable  for  cylin- 
drical shapes  than  the  caliper-gage.  But  the  collar  cannot  be  applied 
to  rectangular  shapes,  nor  can  it  be  applied  to  such  work  as  crank-pins, 
and  similar  work  having  a  small  diameter  between  two  larger  diameters. 
The  cost  is  also  greater  than  that  of  the  caliper-gage. 

Limit-gages   (Fig.    28).  —  The    limit-gage    is    used  where    extreme 
accuracy  is  not  required.     It  is  always  made  with  two  dimensions, 


FIG    28. 


one  larger  and  one  smaller  than  the  nominal  size.     It  is  intended  that 
the  larger  size  shall  go  on,  and  the  smaller  size  not  go  on,  the  work. 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP 


17 


Thus,  if  the  piece  of  work  is  made  of  a  size  between  the  two  sizes  of  the 
gage,  it  is  considered  sufficiently  accurate  for  the  work  in  hand.  The 
difference  between  the  two  sizes  depends  upon  the  quality  of  the  work 
and  may  vary  from  .001  to  .00$  of  an  inch.  The  limit-gage  is  made 
both  in  the  internal  and  external  form. 

Machining  work  to  an  exact  size  is  very  expensive,  and  it  is  obvious 
that  the  limit-gage,  wherever  it  can  be  used,  is  a  great  time-saver.  In 
some  lines  of  machinery,  where  competition  is  very  close,  it  has  been 
found  well-nigh  indispensable.  The  limit-gage  is  a  comparatively 
modern  tool,  and  it  is  not  fully  appreciated;  but  it  will  doubtless  be 
more  generally  used  in  the  future. 

An  Adjustable  Limit-gage  is  shown  in  Fig.  29.  It  will  be  understood 
that  the  adjustment  is  effected  by  the  screws  shown.  These  gages 


FIG.  29. 

could  be  made  with  micrometer-screws  and  thus  the  difference  would 
be  registered. 

A  gage  of  this  form  having  only  one  screw  is  called  a  snap-gage. 

External  and  Internal  Thread-gages. — In  Figs.  30  and  31  are  repre- 
sented external  and  internal  standard  thread-gages.  The  slight  adjust- 
ment provided  in  Fig.  30  is  not  intended  for  different  sizes,  but  rather 
to  compensate  for  wear  of  the  instrument.  In  the  manufacture  of 
taps  and  dies,  and  in  any  other  case  in  which  accurate  measurement 
of  screws  is  necessary,  these  instruments  are  very  reliable.  As  the 
collar  and  plug-gages  are  to  the  micrometer-calipers,  so  are  these  instru- 


18 


MACHINE-SHOP  TOOLS  AND  METHODS 


ments  to  the  screw-thread  micrometer,  and  by  some  they  are  used  in 
preference  to  the  latter  instrument.  The  blank  end  of  Fig.  31  is  a 
gage  for  the  hole  before  thread  is  cut. 


FIG.  30 


FIG.  31. 

Thread-  and  Center-gage  (Fig.  32). — One  of  the  smallest  standard 
gages  used  in  the  machine-shop  is  the  thread-gage.  This  is  used  not 
only  for  testing  the  shape  of  the  thread-tool,  but  also  for  setting  the 
tool  when  cutting  thread  in  the  lathe.  It  is  used  on  U.  S.  standard 


FIG.  32. 

and  V-shaped  threads  for  setting  the  tools,  and  in  grinding  the  tools 
for  V  threads.  It  has  still  another  application:  the  U.  S.  standard 
and  V-shaped  threads,  having  the  same  angle  as  lathe-centers,  60°,  the 
large  V  on  the  end  of  the  gage  is  used  to  test  the  conical  end  of  the  lathe- 
center.  For  this  reason  it  is  sometimes  called  a  center-gage.  The 
use  of  the  instrument  for  setting  a  thread-tool  will  be  more  particu- 
larly described  in  connection  with  the  subject  of  screw-cutting. 

The  gage  shown  in  Fig.  33  is  used  for  testing  the  shape  of  thread- 
tools  for  U.  S.  standard  thread. 

Thread-pitch  Gage  (Fig.  34).  —  The  thread-pitch  gage  is  some- 
times confused  with  the  thread-gage.  The  purpose  of  this  instrument 
is  not  to  test  the  angles  of  the  thread,  but  the  pitch  of  the  thread.  It 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  19 

consists  of  a  number  of  gages  hinged  on  a  common  center,  each  of  which 
is  adapted  to  one  particular  pitch,  which  pitch  is  indicated  on  the  gage. 


FIG.  33. 


Templets.  Distinction  between  Templets  and  Gages.  —  Another 
instrument  used  to  some  extent  is  the  templet.  There  is  some  con- 
fusion in  the  minds  of  mechanics  respecting  the  distinction  between 


FIG.  34. 

templets  and  gages.  A  templet  is  a  pattern  by  which  to  mark  off  the 
shape  of  a  piece  of  work  or  to  mark  positions  for  holes,  etc.  Templets 
are  generally  made  of  sheet  steel.  A  gage  is  a  standard  of  measure- 
ment or  shape,  but  a  gage  may  be  used  as  a  pattern  to  mark  off  a  shape 
or  size,  and  a  templet  may  be  used  to  test  a  shape;  there  is,  therefore, 


20 


MACHINE-SHOP  TOOLS  AND  METHODS 


an  overlapping  of  the  definitions,  hence  the  confusion.  A  gage,  how- 
ever, is  more  frequently  used  for  regular  shapes 
and  sizes,  and  a  templet  for  special  or  more  com- 
plicated shapes. 

Surface-gages. — The  surface-gage  is  quite  a 
departure,  both  in  its  design  and  in  its  use,  from 
any  of  the  instruments  heretofore  described.  A 
typical  form  of  this  tool  is  shown  in  Fig.  35.  It 
consists  of  a  base  similar  to  that  of  an  ordinary- 
lamp,  and  a  central  stem,  which  stem  carries  a 
needle  and  a  clamp  by  which  the  needle  may  be 
held  in  any  position  on  the  stem.  This  instru- 
ment is  used  in  connection  with  a  base-plate  for 
establishing  centers,  marking  center  lines,  etc., 
when  laying  out  work.  It  is  also  used  to  adjust 
work  on  a  planer,  and  sometimes  on  the  lathe  and 
drill-press. 

A  special  design  of  this  instrument  is  so  con- 
structed as  to  admit  of  its  use  on  cylinders.  This 
modified  design  ha£  a  V-shaped  grooved  cut  length- 
wise through  the  base  by  which  the  gage  may  be 
revolved  around  the  cylinder  to  mark  concentric 
circles  on  the  end  of  the  cylinder,  as  shown  in  Fig. 
36.  It  may  also  be  used  for  small  work  in  general. 
Wire-gages,  Twist-drill  Gages,  etc. — There  is  a  class  of  gages  used 

for  measuring  sheet  metal,  wire,  etc.,  in  which  the  sizes,  with  few  excep- 


FIG.  35. 


FIG.  36. 

tions,  are  denoted  by  numbers.  The  most  common  forms  are  the  cir- 
cular disk  with  slots  cut  in  the  periphery,  the  rectangular  plate  with  slots 
in  the  two  edges,  and  the  rectangular  plate  with  a  long  angular  slot 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP 


21 


lengthwise  of  the  plate.;  These  are  shown  in  Figs.  37,  38,  and  39  respect- 
ively. Numbers  near  the  slots  indicate  the  dimensions,  the  wire  or 
the  plate  being  measured  by  passing  either  into  the  slot.  In  the  case 
of  the  gage  having  angular  openings  the  article  is  passed  down  the 


FIG.  37. 


9l  Sl 


000 


00 


FIG.  38. 


FIG.  39. 


slot  until  it  touches  two  sides,  the  number  at  the  points  of  contact  indi- 
cating the  size.  The  method  of  using  the  drill-gage  will  be  readily 
understood. 

As  the  numbers  of  most  of  the  gages  are  arbitrary,  one  must  be 
familiar  with  the  significance  of  the  numbers,  or  consult  a  table  to  ascer- 


22 


MACHINE-SHOP  TOOLS  AND  METHODS 


tain  the  values.  There  would  be  no  serious  trouble  here  were  it  not 
for  the  fact  that  there  are  so  many  different  gages,  and  so  few  persons 
understand  the  usage  prevailing  among  the  manufacturers,  or  the  impor- 
tance of  specifying  the  gage  to  be  used.  Ignorance  on  this  subject  has 
caused  delays,  endless  disputes,  and  sometimes  expensive  lawsuits. 

The  following  table,  which  is  not  complete  for  any  of  the  gages, 
gives  the  names,  numbers,  and  corresponding  values  of  most  of  the 
gages  used  in  this  country,  and  some  that  are  used  in  foreign  countries. 
(8-0,  7-0,  etc.  =00000000,  0000000,  etc.) 


d 

"iS 

.1 

~c 

O 

1 

O  l"~l 

• 

! 

ll 

1« 

1 

| 

14 

1, 

1 

ll 

1 

O 

3 

! 

11 

3 

si 

a 
| 

,d  o5 

1 

M  . 

-  Si 

03  g 

S-xil 

ll 

1 

If! 

1 

o  • 

op 

*o 

£  2 

..-«  ^* 

^3'"' 

3?  §? 

*  »  « 

•?  s 

CO 

•  ^^ 

6 

l« 

2° 

c3  O 

•"c  ^ 

fa 

0  m 

•§ 

K  a 

3 

£^ 

fc 

^ 

H 

•^ 

fl 

OQ 

^ 

^ 

02 

^ 

^ 

H 

i 

2 

3 

4 

5 

6 

7 

8 

9 

13 

11 

P-0 

.00C3 

7-0 

49 

5 

0087 

5 

6-0 

46 

464 

0095 

46875 

5-0 

43 

432 

01 

4375 

450 

4-0 

.46 

.454 

.3938 

.400 

.011 

.40625 

.400 

3-0 

.40964 

.425 

.3625 

.372 



.012 

.03i52 



.375 



.360 

9_Q 

3648 

38 

3310 

348 

0133 

04468 

34375 

330 

1-0 

32486 

34 

3065 

324 

0144 

.05784 

3125 

.305 

1 

.2893 

.300 

.2830 

.300 

.227 

.0156 

.071 

.228 

.28125 

.001 

.285 

2 

.25763 

.284 

.2625 

.276 

.219 

.0166 

.08416 

.221 

.265625 

.002 

.265 

3 

.22942 

.259 

.2437 

.252 

.212 

.0178 

.09732 

.213 

.25 

.003 

.245 

4 

.20431 

.238 

.2253 

.232 

.207 

.0188 

.11048 

.209 

.234375 

.004 

.225 

5 

.  18194 

.22 

.2070 

.212 

.204 

.0202 

.12364 

.2055 

.21875 

.005 

.205 

If  one  will  take  the  time  to  thoroughly  investigate  this  matter,  he 
will  find  that,  notwithstanding  there  are  so  many  wire-gages  in  use  in 
this  country,  there  are  only  three  in  general  use.  The  American  (or 
Brown  &  Sharpe),  the  English  (Birmingham  or  Stubs'  iron  wire),  and 
the  United  States  standard  gage  are  probably  used  in  at  least  95  per 
cent  of  the  cases  where  wire  and  plate  are  measured. 

Chas.  A.  Strelinger  &  Company  of  Detroit,  who  handle  a  variety 
of  brass  wire,  sheet  brass,  etc.,  state  in  their  catalog  that  unless  other- 
wise ordered  brass  manufacturers  furnish  sheet  brass,  hard-drawn 
copper  and  German-silver  wire,  and  brazed  copper  and  brass  tubing 
by  the  American  gage;  while  for  sheet  copper,  regular  copper  and  brass 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP 


23 


wire,  and  seamless  brass  .tubing  they  use  the  English  gage.  The  gage 
of  column  9,  known  as  the  United  States  standard,  was  established  in 
1893  by  Congress  as  the  standard,  for  sheet  and  plate  iron  and  steel. 
It  is  used  in  determining  duties*  and  taxes  on  the  above  materials,  and 
quite  generally  by  manufacturers  $f  sheet  iron  and  steel  for  thicknesses 
below  about  Vie"-  For  heavier  sheets  or  plates  the  Birmingham  gage 
is  used,  as  a  rule.  In  ordering  any  of  the  above  materials  the  gage  to  be 
used  should  be  specified. 

As  the  Stubs'  gages  are  used  extensively  in  America,  it  is  important 
to  distinguish  between  the  Stubs'  wire-gage 
and  Stubs'  steel-wire  gage.  It  should  be 
noted,  also,  that  Stubs'  wire-gage,  the  English 
wire-gage,  and  the  Birmingham  gage  are  one 
and  the  same.  The  Imperial  wire-gage,  which 
was  adopted  by  Parliament  in  1884  as  the 
English  standard,  is  not  used  to  any  great 
extent  in  this  country.  Neither  is  the  "Old 
English"  or  London  gage  (which,  as  shown 
in  the  catalog  of  Merchant  &  Company  of 
Philadelphia,  agrees  with  Birmingham  in  all 
sizes  between  0000  and  18)  used  to  any 
considerable  extent  in  America.  Confusion 
respecting  the  identity  of  the  gages  will,  in 
a  large  measure,  be  avoided  by  attention  to 
the  names  given  in  the  preceding  table. 

The  Twist-drill  Gage  of  column  8  and 
Fig.  40,  though  sometimes  used  for  measur- 
ing wire,  is  the  Stubs'  drill-gage,  and  differs 
but  little  from  the  Stubs'  steel-wire  gage, 
with  which  it  is  sometimes  confused.  Indeed, 
it  follows  Stubs'  steel-wire  gage  exactly  for 
sizes  larger  than  No.  1,  which  sizes  in  both 
of  these  gages  are  designated  by  letters. 
Thus,  A  =  .234"  diameter,  B  =  .238"  diameter, 
etc.,  the  largest  size,  Z,  equaling  .413"  diam- 
eter. This  gage  is  practically  the  standard  of  numbered  drill-gages  for 
the  United  States.  It  is  very  seldom  that  any  other  numbered  gage  is 
used  for  measuring  drills  in  this  country. 

There  is  a  drill-gage  in  common  use  known  as  the  "jobbers'"  drill- 
gage,  on  which  numbers  are  not  used.     On  this  gage  the  dimensions  are 


FIG.  40. 


24 


MACHINE-SHOP  TOOLS  AND  METHODS 


given  in  binary  divisions  of  the  inch,  and  it  includes  all  the  sizes  between 
Vie  and  1/2  inch  by  sixty-fourths  of  an  inch. 

The  Gage  for  Wood  and  Machine  Screws  is  regarded  as  the  standard 
of  numbered  gages  in  America  for  the  purposes  indicated,  although  the 
jobbers'  drill-gage  is  used  to  some  extent  for  " fractional  sizes"  (Vie, 
Vs,  etc). 

We  cannot,  within  the  space  of  this  work,  discuss  the  principles 
of  the  various  gages,  but,  because  of  its  radical  and  significant  difference, 
the  theory  of  the  Edison  gage  is  briefly  outlined.  The  Engineering 
Department  of  the  Edison  Company  designed  this  gage  with  special 
reference  to  electrical  requirements.  It  is  based  on  the  sectional  area 
of  the  wire,  the  number  indicating  the  number  of  thousands  of  circular 
mils.  A  few  sizes  are  here  given: 


Gage  Number. 

Circular  Mils. 

Diameter  in  Mils. 

3 

3000 

54.  78 

5 

5000 

70.72 

8 

8000 

89.45 

12 

12000 

109.55 

This  gage  has  not  come  into  general  use,  the  American  gage  still 
being  extensively  used  for  measuring  wire  for  electrical  purposes. 

Because  of  the  confusion  arising  from  the  use  of  gages,  there  is  a 
growing  tendency  to  specify  the  size  of  wire  and  sheet  metal  in  thousandths 
of  an  inch.  Accordingly,  we  have  the  decimal  gage,  shown  in  Fig.  41, 
and  the  Whitworth  gage,  referred  to  in  column  10  of  the  table.  But 
as  gages  are  more  or  less  unreliable  on  account  of  wear,  the  micrometer- 
caliper  is  used  when  great  accuracy  is  required. 

In  answer  to  an  inquiry  as  to  whether  the  mills  would  roll  to  any 
decimal  of  an  inch  without  extra  charge,  Merchant  &  Company  of  Phila- 
delphia replied: 

"Mills  that  are  rolling  sheet  brass  or  wire  are  quite  willing  to  roll 
to  decimals  of  an  inch,  but  it  is  a  very  difficult  matter  to  get  any  mills 
that  are  rolling  steel  or  drawing  steel  wire  to  guarantee  decimals  of  an 
inch  unless  they  receive  a  special  price  for  the  work." 

From  what  has  been  said  respecting  gages  it  will  be  observed  that 
a  wire-gage  may  be  used  for  both  wire  and  sheet  metal,  and  that  a  twist- 
drill  gage  is  sometimes  used  for  measuring  wire  and  screws  as  well  as 
twist  drills. 

The  Key-seat  Rule  is  an  instrument  used  in  drawing  parallel  lines 
on  cylinders,  as  in  marking  off  key-seats.  It  is  shown  in  Fig.  42.  Fig.  43 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP 


25 


shows  the  method  of  applying  it  to  a  shaft.  Slight  pressure  at  P  causes 
the  two  edges  to  lie  parallel  with  the  axis  of  the  shaft,  when  the  lines 
may  be  drawn  along  the  edge  w^th  a  scriber. 


FIG.  41. 


FIG.  42. 


FIG.  43. 


FIG.  44. 


Machinists'  Try-squares. — It  is  unnecessary  to  enter  into  a  lengthy 
description  of  machinists'  squares.  A  brief  reference  to  a  few  of  the 
more  modern  instruments  will  be  sufficient.  Fig.  44  shows  a  square 


26 


MACHINE-SHOP  TOOLS  AND  METHODS 


with  three  different  blades.  Each  blade  fits  into  the  stock,  and  is  held 
and  adjusted  by  means  of  the  thumb-nut  shown  at  bottom  of  the  stock. 
One  of  the  blades  is  shaped  to  30  and  45  degrees  on  the  two  ends.  The 
narrow  blade  is  very  convenient  for  die-sinking  and  similar  fine  work. 
The  special  feature  of  this  square  is  the  provision  for  endwise  adjust- 
ment of  the  blades. 

The  Combination  Square  shown  in  Fig.  45  is  very  much  in  favor. 
It  combines  in  one  instrument  a  square,  center  head,  bevel  protractor, 
spirit-bevel,  and  rule.  Each  of  the  first  four  may  be  quickly  detached 
or  used  interchangeably  with  the  rule.  While  these  tools  are  fairly 


FIG.  45. 

reliable,  it  is  not  likely  that  they  can  be  depended  upon  to  hold  their 
original  accuracy  as  long  as  the  best  solid  steel  square  with  hardened 
stock  and  blades. 

Fig.  46,  which  is  taken  from  an  article  by  "E.  A.  R."  in  the 
''American  Machinist/'  vol.  27,  page  287,  shows  how  the  combination 
square  may  be  used  to  measure  tapers.  The  degree  of  taper  is  in- 
dicated on  the  instrument . 

Fig.  47  shows  a  universal  bevel  protractor,  and  Fig.  48  shows  its 
application  to  a  variety  of  cases. 

In  the  preceding  pages  we  have  described  the  principal  measuring- 
instruments  used  in  the  machine-shop,  and  have  referred  to  the  high 
degree  of  accuracy  possible  in  the  use  of  some  of  these  tools.  But  it 
should  be  understood  that  different  classes  of  work  require  different  degrees 
of  accuracy,  and,  other  things  being  equal,  he  is  the  best  mechanic  who 
knows  about  what  degree  of  refinement  is  needed  in  each  case.  One 
may  be  a  very  skillful  workman  and  yet  be  a  failure  from  a  commercial 


THE  MEASURING   SYSTEM  OF  THE  MACHINE-SHOP  27 


American.Machinwt 


FIG.  46. 


FIG.  47. 


28 


MACHINE-SHOP  TOOLS  AND  METHODS 


standpoint.  It  was  this  difference  in  judgment  that  led  to  the  inven- 
tion and  development  of  the  limit-gage.  There  is  an  impression  that 
this  instrument  was  designed  for  very  fine  and  accurate  work,  but  from 


THE  L.S.STARRETT  CO. 
ATHOL.MASS.  U.S.A. 


FIG.  48. 

the  above  considerations,  and  what  was  previously  said  in  this  con- 
nection, it  will  be  seen  that  the  limit-gage  is  intended  rather  to  pre- 
vent workmen  from  wasting  time  by  being  more  exact  than  necessary. 
Caliper-gages  and  collar-  and  plug-gages  are  adapted  to  a  higher  degree 
of  accuracy.  As  the  plug-gage  will  not  enter  the  hole  until  the  latter 


THE  MEASURING  SYSTEM  OF  THE  MACHINE-SHOP  29 

is  as  large  as  the  gage,  it  is  necessary  to  use  common  machinists'  calipers 
or  some  other  adjustable  measuring-tool  in  connection  with  this  gage. 
The  same  remark  applies  to  inside  caliper-gages,  and  with  slight  modi- 
fication to  collar-  and  caliper-gages  for  outside  measurements. 

A  Peculiar  Phenomenon. — §,uch  tools  as  caliper-  and  plug-gages 
are  machined  to  approximate  dimensions  of  untempered  steel  and  then 
hardened.  Later  they  are  ground  to  final  dimensions  by  special 
machinery.  But  the  steel  seems  to  resent  being  subjected  to  any  treat- 
ment immediately  after  the  hardening  process.  Following  this  fiery 
ordeal  the  metal  requires  a  prolonged  rest.  If  not  allowed  this  "sea- 
soning," the  gages  will  change  in  size  or  become  otherwise  distorted. 
Several  months  are  required  to  thoroughly  season  such  tools. 


CHAPTER  II 
THE  HAMMER  AND  ITS  USE 

Three  Common  Forms  of  the  Hammer — Material,  Weight,  etc. — 

The  hammer  is  one  of  the  oldest  instruments  connected  with  industrial  art. 
To  trace  its  invention  would  necessitate  a  search  through  the  remotest 
records  of  history.  Notwithstanding  its  resonant  din  was  not  per- 
mitted within  the  walls  of  Solomon's  temple,  this  humble  tool  was 
indispensably  associated  with  some  of  the  noblest  structures  of  antiquity. 


FIG.  49.  FIG.  50.  FIG.  51. 

The  three  forms  of  the  hammer  in  most  common  use  are:  first,  ham- 
mer with  flat  peen  parallel  to  handle  (Fig.  49);  second,  hammer  with 
flat  peen  at  right  angles  to  the  handle  (Fig.  50) ;  and  third,  the  ball-peen 
hammer  (Fig.  51).  Hammers  are  always  made  of  tool-steel  and  tem- 
pered on  each  end  about  as  hard  as  they  will  stand  without  breaking, 
the  eye  being  left  soft.  As  used  in  the  machine-shop  they  are  made 
in  sizes  varying  from  6  to  28  ounces.  The  smaller  sizes,  from  6  to  16 

30 


THE  HAMMER  AND  ITS  USE  31 

ounces,  are  used  for  light  riveting,  laying  out  work,  etc.  The  heavy 
sizes  are  used  for  heavy  riveting,  chipping,  and  for  general  shop  work. 
The  word  "peen"  refers  to  the  upper  end  of  the  hammer — the  end 
used  in  riveting.  Used  as  a  verb,  it  means  to  stretch  by  hammer-blows, 
as  in  straightening  a  shaft.  The^ther  end  of  the  hammer  is  called 
the  head.  The  opening  "in  the  center,  called  the  eye,  is 
oval-shaped  and  made  flaring  or  larger  at  each  end  than  in 
the  middle.  The  handle  should  be  so  fitted  to  the  eye  that 
a  plane  passing  through  the  axis  of  the  hammer  would  bisect 
the  handle  through  its  long  diameter,  as  at  A B,  Fig.  52. 
If  the  handle  be  otherwise  set,  a  slight  twisting  motion 
of  the  workman's  hand  will  be  necessary  in  order  to  make 
the  hammer  strike  a  square  blow.  Some  authorities  say 
that  the  handle  should  set  at  right  angles  to  the  axis  of 
the  hammer,  but  the  writer  has  observed  that  many  ma- 
chinists prefer  to  incline  the  handle  slightly  in  the  direction 
of  the  hammer-head.  It  should  never  incline  in  the  oppo-  '  F  ' 
site  direction.  The  hammer  is  held  on  the  handle  by  a 
small  metal  wedge  which  spreads  the  end  of  the  handle,  causing  it  to 
fill  the  flaring  eye.  The  wedge  should  be  nicked  somewhat  like  a  rasp 
to  keep  it  from  being  jarred  loose.  In  order  to  impart  a  certain  flexi- 
bility to  the  handle  it  is  made  of  smaller  cross-section  near  the  ham- 
mer or  at  the  neck  of  the  handle.  The  shock  of  the  blow  is  by  this 
means  partly  neutralized  and  the  use  of  the  hammer  is  rendered  less 
tiresome.  That  part  of  the  head  which  takes  the  blow  is  called  the 
face.  It  is  made  slightly  "crowning,"  or  high  in  the  center. 

Proper  Method  of  Using  the  Hammer. — Some  persons  swing  a  ham- 
mer as  they  would  a  bat.  This  is  a  very  awkward  method.  In  striking 
a  blow  the  hammer  should  move  in  a  plane  but  slightly  inclined  from 
the  vertical.  In  using  the  hammer  the  handle  should  not  be  gripped  in 
the  middle,  as  the  beginner  is  likely  to  do,  but  near  the  end;  and  for  the 
heaviest  work  it  should  be  held  at  the  extreme  end.  In  this  connection 
the  writer  recalls  a  story,  read  in  some  technical  journal,  which  is  sub- 
stantially as  follows:  Bill  Shirk  applied  to  John  Littlepay  &  Co.  for  a 
"job,"  and  was  set  to  work  at  $1.75  per  day.  Soon  afterward  the  fore- 
man noticed  that  Shirk  held  his  hammer  near  the  neck  of  the  handle, 
and  spoke  to  him  about  it.  In  replying,  Shirk  held  up  the  hammer, 
exposing  three  marks  on  the  handle.  The  first  was  $1.75,  the  middle  one 
$2.50,  and  the  mark  on  the  extreme  end  $3.  He  explained  that  the 
marks  indicated  the  relation  between  wages  and  work,  and  that  it  was 


32 


MACHINE-SHOP  TOOLS  AND  METHODS 


against  his  principles  to  do  S3  work  for  $1.75  pay.  Now  that  man's 
principles  were  entirely  wrong.  Not  only  does  it  make  one  appear 
awkward  and  inexperienced  to  grip  the  hammer-handle  at  the  neck, 
but  when  the  motive  is  that  of  Bill  Shirk,  or  when  the  workman  is  so 
particular  about  gaging  his  work  according  to  wages,  he  is  very  likely 
to  have  to  continue  at  low  wages.  Furthermore,  such  a  conception  of 
one's  calling,  however  humble  that  calling  may  be,  is  degrading.  Work 
is  simply  another  word  for  duty,  and  that  word  is  sacred.  "My  Father 
worketh  hitherto  and  I  work,"  said  the  Divine  Teacher.  Then  let  us 
give  to  life's  duties  the  best  that  is  in  us,  whether  we  get  "value  received " 
or  not. 

Striking  Two  Blows  for  One. — Another  awkward  practice  on  the 
part  of  the  novice  is  that  of  striking  two  blows  for  one — a  heavy  blow  and 
then  a  light  one.  The  student  may  as  well  overcome  this  fault  in  the 
beginning.  He  can  make  but  little  progress  after  this  fashion. 

Riveting. — The  peen  end  of  a  hammer  is  used  mainly  for  peening 
and  riveting.  The  word  peen  has  already  been  denned.  Riveting  is 
the  process  of  upsetting  by  hammer-blows,  or  by  machine,  a  pin  or  rivet 
to  fasten  two  pieces  of  metal  together.  Riveting  as  used  in  connection 


FIG.  53. 

with  boilers  is  sometimes  done  by  hand  and  sometimes  by  machine,  and 
the  rivets  are  always  heated.  In  riveting  in  the  machine-shop  the  rivet, 
as  a  rule,  is  cold.  A  plain  pin  is  inserted,  as  at  C  (Fig.  53),  and  the  ends 
hammered  down  to  fill  the  countersink,  as  at  D  or  E\  or  a  rivet  is  used, 
as  at  F,  in  which  case  one  end  only  is  riveted.  While  one  end  of  the 
rivet  is  being  hammered  the  other  end  must  be  supported  by  an  anvil  or 
any  other  suitable  means. 

Figs.  54  and  55  show  a  special  method  for  riveting  large  pins.  For 
this  method  the  pin  is  placed  in  the  lathe  and  the  end  recessed  or  cupped 
out,  leaving  a  circular  edge  or  ring  B  to  be  pounded  down,  rather  than 
the  whole  end  area  of  the  rivet.  This  method  is  sometimes  used  for  the 
crank-pins  of  engines,  and  may  be  used  on  any  pins  of  about  one  inch 


THE  HAMMER  AND  ITS  USE 


33 


in  diameter  and  larger.  If  the  end  of  the  rivet  is  to  present  a  rounded  or 
crowned  finish,  care  should  be  taken  that  the  pin  be  made  long  enough 
to  have  the  bottom  of  the  recessed  surface  project  slightly  beyond  the 
surface  of  the  crank  disk  or  other  work  for  which  the  rivet  may  be  used. 

In  riveting,  the  force  of  the  blow  should  be  proportioned  to  suit 
the  size  of  the  rivet ;  comparatively  speak- 
ing, light  blows  affect  the  end  of  the  rivet, 
while  heavy  blows  tend  to  bulge  the  rivet  in 
the  center  respecting  its  length. 

Straightening  Shafts  by  Peening,  by 
Screw-press,  etc. — In  the  case  of  a  bent  or 
curved  shaft  the  concave  side  of  the  shaft 


FIG.  54. 


FIG.  55. 


is  shorter  than  the  convex  side,  and  in  straightening  the  shaft  it  is 
required  to  make  the  two  sides  equal  in  length.  That  the  concave 
side  is  shorter  than  the  convex  will  be  apparent  if  we  consider  the 
curved  shaft  as  the  sector  of  a  circle :  if  sufficiently  extended,  the  shaft 
will  make  a  complete  circle. 

One  method  of  straightening  such  a  shaft  is  to  place  it  on  the  centers 
in  the  lathe,  pry  up  the  convex  side  by  a  lever,  and  peen  by  light  ham- 
mer-blows the  upper  side.  This  should  be  repeated  until  the  shaft  is 
found  to  be  straight.  To  find  the  convex  side  of  a  shaft  we  revolve 
the  shaft  in  the  lathe  and  move  a  piece  of  chalk  carefully  toward  the 
shaft  until  it  touches  the  latter.  The  chalk  will  mark  the  convex  side. 
As  a  more  accurate  method  we  may  fasten  a  tool  in  the  tool-post  of  the 
lathe,  and,  while  running  the  lathe  backwards,  feed  the  tool  toward  the 
shaft  until  it  touches  the  convex  side.  This  method  of  straightening 
shafts  applies  in  the  case  of  an  old  shaft,  but  is  not  adapted  to  shafts 
which  have  to  be  machined.  The  reason  why  it  is  not  adapted  to  shafts 
which  have  to  be  machined  or  turned  is  that  the  peening  affects  only  the 
outer  surface  of  the  shaft,  and  the  turning  removes  this  outer  surface, 
thereby  partially  neutralizing  the  effect  of  the  peening. 

For  straightening  shafts  which  are  to  be  turned  the  screw-press  method 
should  generally  be  used,  and  in  the  case  of  a  very  large  shaft  it  is  some- 


34  MACHINE-SHOP  TOOLS  AND  METHODS 

times  necessary  to  heat  the  shaft.  Lathes  designed  especially  for  turn- 
ing shafting  are  generally  provided  with  a  suitable  screw-press.  This 
device  consists  essentially  of  a  base  and  U-shaped  standard,  with  a  large 
screw  passing  through  the  projecting  arm  of  the  standard.  It  usually 
has  four  rollers  designed  to  roll  along  the  ways  of  the  lathe.  When 
a  shaft  is  to  be  straightened  it  is  placed  in  the  lathe  and  the  convex  side 
found  as  above  described.  The  press  is  now  moved  along  the  ways  of 
the  lathe  until  the  screw  is  about  central  with  the  convex  portion  of 
the  shaft.  With  the  convex  side  of  the  shaft  uppermost,  and  the  under 
side  of  the  shaft  supported  at  two  points  on  the  base  of  the  press,  the 
pressure  is  applied  by  the  screw  and  a  lever.  The  screw  is  next  released 
and  the  shaft  again  revolved  to  ascertain  if  the  curved  portion  has  been 
straightened.  When  straight  the  chalk  will  make  a  continuous  mark 
around  the  shaft;  if  not  straight,  the  process  is  repeated. 

Straightening  a  Long  Bar  of  Cast  Iron. — For  straightening  a  bar 
of  cast  iron  (not  a  regular  shaft)  we  usually  ascertain  the  point  of  curva- 
ture by  means  of  a  straight-edge.  Having  found  the  convex  portion, 
it  is  placed  over  an  anvil  or  other  suitable  support,  with  concave  side 
up,  and  pressure  applied  by  hand  to  the  ends  of  the  bar.  The  bar  is 
then  peened  on  the  concave  side  and  again  tested  with  straight-edge, 
the  process  being  repeated  until  the  bar  is  found  to  be  straight. 

There  is,  however,  another  method  which  has  some  advantages; 
this  we  call  the  dropping  process.  The  bar  or  slab  is  dropped  over  a 
solid  block  of  wood,  the  convex  side  striking  the  wood  and  the  curvature 
being  corrected  by  the  momentum  of  the  free  ends  of  the  bar.  This 
avoids  the  bruising  incident  to  the  peening  process,  and  in  the  hands 
of  skillful  workmen  gives  very  satisfactory  results.  Care  should  be 
taken,  however,  to  avoid  dropping  the  bar  too  heavily,  as  there  is  some 
danger  of  breaking  it.  A  bar  of  cast  iron  may  also  be  broken  by  applying 
too  great  pressure  while  peening  it. 

Peening  a  Connecting-rod  Strap. — That  detail  on  a  steam-engine 
which  binds  the  crank-pin  brasses  to  the  connecting-rod  is  called  a  strap, 
or  a  connecting-rod  strap.  There  is  also  the  cross-head  strap  and  the 
eccentric-strap,  the  latter  serving  a  somewhat  different  purpose  from 
the  other  two.  Fig.  56  shows  a  connecting-rod  strap.  From  various 
causes,  sometimes  due  to  errors  in  machining  the  straps,  and  at  other 
tunes  due  to  hard  usage,  these  straps  become  spread,  so  that  the  opening 
is  wider  at  A  than  at  B.  A  knowledge  of  peening  is  very  useful  in  this 
case.  By  holding  the  strap  over  a  block  of  copper,  or  Babbitt  metal, 
or  hard  wood,  and  applying  pressure  by  a  carpenter's  clamp  or  other- 


THE  HAMMER  AND  ITS  USE 


35 


FIG.  56. 


FIG.  57. 


wise  to  draw  the  strap  sides  closer  together  at  A ,  the  strap  may  be  peened 
by  light  hammer-blows  at  C  until  the  error  is  corrected      If  the  sides 
of  the  strap  at  A  be  too  close  to- 
gether, the  peening  would  of  course 
be  needed  on  the  opposite  side. 

Enlarging  a  Piston-ring  by 
Peening. — Fig.  57  shows  one  form 
of  piston-packing  or  a  piston-ring. 
The  object  of  this  device  is  to  form 
a  steam-tight  joint  between  the 
walls  of  a  steam-engine  cylinder 
and  its  reciprocating  piston.  This 
form  of  ring  is  commonly  made 
slightly  larger  in  diameter  than  the 

cylinder-bore,  and  sprung  to  its  place  on  the  piston.  If  by  long  usage 
it  becomes  too  small  to  make  a  good  joint,  it  may  be  enlarged  by  peen- 
ing the  inside  surface.  The  ring  should  be  supported  on  a  block  of 
hard  wood  or  bar  of  Babbitt  metal,  and  lightly  peened  throughout  its 
inner  circumference,  being  frequently  tested  to  ascertain  whether  it 
has  been  sufficiently  spread.  Piston-rings  are  usually  made  of  cast 
iron  and  special  care  is  required  in  peening  light  sections  of  this  material. 

Soft  Hammers. — There  is  a  modified  form  of  hammer,  sometimes 
called  a  mallet,  which  should  be  used  more  frequently  in  the  machine- 
shop  than  it  is.  These  hammers  are  made  of  copper,  Babbitt  metal, 
or  rawhide,  and  are  used  for  driving  mandrels  in  work  or  adjusting 
work  in  the  lathe,  and  in  any  case  where  it  is  desirable  to  avoid  marring 


Raw  Hide 


FIG.  58. 


FIG.  59. 


finished  work.  In  the  absence  of  such  a  hammer  a  block  of  hard  wood 
may  be  used  in  connection  with  the  ordinary  hammer.  For  mandrels, 
however,  a  mandrel-press  should  be  used  when  one  is  available,  though 
many  shops  lack  such  a  machine.  Figs.  58  and  59  show  respectively 
a  rawhide  mallet  and  a  lead  mallet.  A  rawhide  mallet  is  made  with 


36  MACHINE-SHOP  TOOLS  AND  METHODS 

detachable  heads  or  "faces"  A,  which  fit  in  the  metal  (east-iron  or  drop 
forging)  part  of  the  hammer  as  shown.  Extra  faces  are  furnished  very 
cheaply  by  machinery  supply  houses.  In  the  lead  mallet  the  body  B 
may  be  made  of  cast  iron,  the  lead  being  held  in  the  dovetail  openings 
on  the  ends.  These  lead  faces  may  extend  about  3/47/  outside  the  cast 
iron,  and  for  forming  the  faces  a  kind  of  open-and-shut  mold  enclosing 
the  iron  body  may  be  used.  Such  molds  may  be  purchased  at  the  ma- 
chinery supply  stores. 


CHAPTER  III 

CHISELS:  THEIR  FORMS  AND  USES 

Names  of  Machinists'  Chisels. — Machinists'  chisels  are  distinguished 
from  other  chisels  by  not  having  handles.  They  are  generally  made 
of  3/4"  octagonal  tool-steel,  and  about  8"  long  when  new,  although 
for  very  delicate  work  they  are  sometimes  made  of  1/2"  steel.  The 
most  common  forms  are  the  flat  and  cape  chisels.  Other  chisels  used 
less  frequently  are  the  side  chisel,  the  diamond-point  chisel,  the  cow- 
mouth  and  the  oil-groove  chisels.  The  key-drift  and  pin-drift,  while 
somewhat  similar  to  the  chisel,  are  used  for  different  purposes.  The 
center-punch  and  drift  are  modifications  of  the  chisel. 

The  Flat  Chisel  (Fig.  60).— The  flat  chisel  is  tapered  and  flat- 
tened about  J/3  its  length  to  the  cutting  edge,  which  is  about  3/32" 
thick  on  the  3/4"  steel  and  proportion- 
ally  thinner  on  smaller  steel.  The  smaller 
chisels  are  also  proportionally  shorter. 
The  flat  chisel  should  be  forged  about 
Vie"  wider  at  the  cutting  end  excepting 


when  made  especially  for  such  soft  metal  ~"jT 

as   Babbitt,   when   it   may   be   made   as 

much  as  50  per  cent  wider.  But  unless  there  is  a  considerable  quantity 
of  such  work  to  do  it  will  be  hardly  worth  while  to  keep  special  chisels 
for  the  purpose.  It  will  pay,  however,  to  grind  the  chisel  to  a  sharper 
angle  for  the  softer  metals,  30°  included  angle  being  about  right  for 
Babbitt  metal,  lead,  and  copper.  For  chipping  brass  and  reasonably 
soft  cast  iron  45°  will  answer,  while  for  average  steel  60°  would  be 
about  right. 

The  experienced  workman  will  not  require  a  gage  to  test  the  chisel 
angle,  but  common  angles,  such  as  are  found  on  certain  tools,  have 
been  named  as  being  convenient  for  those  who  prefer  to  use  a  gage. 
Thus  the  chisel  for  steel  may  be  tested  by  a  center-gage,  which  should 
be  carried  in  every  machinist's  kit. 

37 


38  MACHINE-SHOP  TOOLS  AND  METHODS 

The  flat  chisel  should  be  so  ground  that  the  center  line  CL  in  Fig.  60 
shall  bisect  the  angle  of  cutting  edge,  or  angle  a.  Looking  at  the  other 
view,  the  end  of  the  chisel  may  be  square  with  the  center  line, 
or  slightly  rounded,  as  at  R.  Many  machinists  think  they  can  do 
smoother  chipping  with  the  chisel  thus  rounded. 

A  fault  that  the  beginner  is  very  likely  to  fall  into  is  that  of  grinding 
D         the  extreme  end  at  an  angle  with  the  flat  sides, 
<Q  as  at  EF,  Fig.  61.   The  line  formed  at  EF  should, 
D         of  course,  be  parallel  with   the  sides,   and  the 
FIG.  61.  two  facets  D  should  be  quite  flat. 

The  Cape-chisel. — All  that  has  been  said  respecting  the  flat  chisel 
applies  equally  well  to  the  cape-chisel,  excepting  that  the  sides  at  right 
angles  to  the  cutting  edge  are  narrower  than  the  shank  (octagonal 
part),  and  that  the  sides  at  right  angles  to  these  are  spread  wider  where 
they  join  the  shank.  The  cape- 


chisel  will  cut  up  some  ugly  capers  "  "~~  Tl  *!TI- 

if  not  properly  forged  and  ground.    (  /^  * — ^     111 

If  not  made  narrower  at  AB  than  FIG.  62. 

GH  (see  Fig.  62),  it  will,  when  the 

corners  wear  dull  or  tapering  at  GH, 

wedge   and   possibly  break   open  a 

frail  piece  in  which  it  is  being  used  FIG.  63. 

to  cut  a  slot.     Referring  to  the  end 

view,  if  the  sides  IJ  are  not  ground  approximately  at  right  angles  with 

KL,  the  chisel  will  twist  and  hang,  and  cannot  be  accurately  guided 

in  a  slot  or  keyway.     Fig.  63  shows  a  side  view  of  the  cape-chisel. 

The  Uses  of  Flat  and  Cape  Chisels. — The  flat  chisel  is  used  prin- 
cipally on  flat  surfaces,  but  it  is  also  used  for  general  chipping.  If 
we  have  a  light  cut  to  take  from  any  metal  surface,  we  use  the  flat 
chisel,  but  if  we  are  to  cut  Vs"  deep,  or  deeper,  it  is  better  to-  precede 
the  flat  chisel  by  grooves  cut  with  the  cape-chisel.  The  distance  apart 
of  these  grooves  should  be  less  than  the  width  of  the  flat  chisel,  thus 
leaving  narrow  strips  to  be  chipped  by  the  latter.  This  method  is 
used  in  chipping  broad  surfaces,  but  it  is  unnecessary  when  the  area 
is  quite  small.  The  surface  shown  in  Fig.  64  represents  this  prepara- 
tory grooving  with  the  cape-chisel;  the  intervening  strips  are  to  be  cut 
away  with  the  flat  chisel. 

There  are  other  uses  for  the  cape-chisel  than  that  just  described. 
It  is  used  for  cutting  keyways  in  shafts,  pulleys,  gears,  etc.;  also  for 
cutting  slots.  In  cutting  a  slot  with  the  cape-chisel,  however,  the 


CHISELS:    THEIR  FORMS  AND  USES 


39 


bulk  of  the  metal  is  generally  removed  by  drilling.     Fig.  65  shows  a 
finished  slot.     This  slot  M  was  first  drilled  with  a  drill  l/^2  of  an  inch 


FIG.  64. 


FIG.  65 

smaller  than  the  finished  size,  the  distance  apart  of  the  centers  of  the 
holes  being  equal  to  the  width  of  the  slot.     The  metal  between  the 


40 


MACHINE-SHOP  TOOLS  AND  METHODS 


holes  is  cut  out  with  a  cape-chisel,  and  finished  smoothly  with  a  file. 
When  slots  are  deep,  say  1V2"  or  more,  we  sometimes  trim  the  sides 
with  a  side  chisel.  The  latter  is  seldom  used  for  any  other  purpose. 

In  cutting  a  keyway  with  the  cape-chisel,  if  the  keyway  be  made 
6/s  of  an  inch,  or  narrower,  the  chisel  should  be  about  1/32  of  an  inch 
narrower  than  the  finished  keyway.  The  remainder  is  removed  by 


FIG.  66. 


FIG.  67. 


FIG.  68. 


FIG.  69. 


the  file.     If  the  keyway  be  3/4">  or  wider,  it  is  better  to  use  a  cape- 
chisel  less  than  half  the  width  of  keyway  and  cut  two  grooves. 

Forms  afld  Uses  of  Other  Chisels.— The  diamond-point  chisel  shown 
in  Figs.  66  and  67  tak^s  its  name  from  the  fact  that  a  cross-section 
near  the  point  is  approximately  diamond-shaped.  It  is  used  for  cutting 
holes  in  boiler-plate,  to  correct  errors  in  holes  while  drilling,  and  some- 
times for  chipping  oil-grooves  in  bearings.  For  the  latter  purpose,  how- 
ever, the  oil-groove  chisel  shown  in  Figs.  68  and  69  is  preferable.  It 


CHISELS:    THEIR  FORMS  AND   USES 


41 


is  merely  a  diamond-point  chisel  with  the  cutting  end  curved  to  facilitate 
its  use  for  the  purpose  named. 

The  Side  Chisel  differs  from  the.  flat  chisel  only  in  having  the  taper 
all  on  one  side,  as  in  Fig.  70.  Its  use  has  already  been  referred  to. 

The  Cow-mouth  Chisel  derives^  its  name  from  its  curved  shape; 
a  better  name  would  be  gouge.  It  is  shaped  somewhat  similar  to  the 
carpenter's  gouge  and  is  used  for  enlarging  holes  or  chipping  curved 
surfaces.  See  Figs.  71  and  72. 


FIG.  70. 


FIG.  71. 


FIG.  72. 


FIG.  73. 


A  Center-punch  is  a  short  punch  with  a  conical  point.  It  is  used 
in  connection  with  the  hammer  to  indent  the  centers  and  circles  in  work 
preparatory  to  drilling,  and  in  a  similar  manner  to  establish  lines  in 
laying  out  work  in  general.  In  laying  out  machined  surfaces  it  is  often 
more  accurate  to  depend  upon  the  lines,  which  in  this  case  should  be 
very  clearly  denned.  Templets  for  important  cams,  etc.,  are  often 
made  of  sheet  steel  in  the  condition  in  which  it  comes  from  the  mill. 
To  prepare  such  a  surface  for  laying  out  it  may  be  coated  with  a  solution 
of  blue  vitriol.  Thus  prepared  the  surface  is  in  shape  to  take  sharply 
denned  and  permanent  lines.  Fig.  73  shows  a  set  of  center-punches; 


42  MACHINE-SHOP  TOOLS  AND  METHODS 

two  punches,  one  for  punching  small  indentations  in  laying  out  work,  and 

a  larger  one  for  drilling,  are  sufficient. 

A  Drift  (Fig.  74)  is  a  tool  that  is  sometimes  used  instead  of  a  file 

for  enlarging  holes,  especially  rectangular  holes.  For  the  latter  pur- 
pose the  cutting  end  is  made  of  rectangular 
cross-section  and  equal  in  width  to  the  finished 
hole.  The  drift  has  no  proper  cutting  edge, 
but  the  end  is  at  right  angles  to  the  body  and 
cuts  on  the  same  principle  as  the  punch  used 
in  punching  holes  in  boiler-plate.  It  is  driven 
by  hammer-blows. 

The  Key-drift  is  a  tool  for  driving  keys 
out  of  pulleys,  gears,  etc.  Like  the  drift  its 
small  end  is  rectangular  in  cross-section,  but 
it,  of  course,  is  not  intended  to  do  any  cutting. 

FIG.  74.  FIG.  75  See  FiS-  75- 

The  Pin-drift  is  merely  a  round  tapering 

punch  for  driving  out  pins  which  are  used  to  hold  such  machine  ele- 
ments as  crank-handles,  levers,  etc.  It  is  shaped  like  the  center-punch, 
excepting  that  the  point  is  flat  and  the  taper  longer. 

Smooth  Chipping.  Precaution  to  Avoid  Breaking  Edge  off  of  Work, 
etc. — In  chipping,  the  chisel  should  not  be  held  near  the  cutting  end, 
but  near  the  head.  To  do  smooth  work  it  is  necessary  to  maintain  a 
constant  inclination  of  chisel  to  the  surface  being  chipped.  The  proper 
inclination  is  easily  determined  during  the  first  few  blows  of  the  hammer. 
If  the  angle  be  too  great,  the  chisel  will  cut  too  deep;  if  too  small,  the 
chisel  soon  ceases  to  cut.  The  smaller  the  angle  between  center  line 
of  chisel  and  surface  of  work,  within  the  above  limitations,  the  more 
effective  are  the  hammer-blows,  and  consequently  the  greater  the  amount 
of  work  accomplished.  But  the  smaller  this  angle,  the  sharper  must 
the  angle  at  cutting  edge  be  ground,  and  this,  also,  is  limited  by  con- 
siderations previously  indicated,  viz.,  the  chisel  edge  will  get  blunt 
too  quickly  if  ground  to  too  sharp  an  angle. 

The  chisel  should  be  kept  well  up  against  the  shoulder  formed  by 
the  cut.  If  a  particle  of  metal  or  a  small  chip  gets  under  one  corner 
of  the  chisel,  it  will  cause  that  corner  to  lift.  A  blow  struck  at  that 
instant  will  cause  the  opposite  corner  to  cut  below  the  chipping 
line. 

When  the  chisel  approaches  the  edge  of  the  surface  it  should  be 
reversed,  or  the  cut  should  be  taken  at  right  angles  to  the  preceding 


CHISELS  :    THEIR  FORMS  AND  USES  43 

cut.     Otherwise  the  edge:  of  the  metal,  especially  if  it  be  cast  iron,  is 
likely  to  be  broken. 

Precautions  in  Grinding  the  Chisel. — In  drawing  the  temper  on  the 
chisel  it  should  be  plunged  in  watej  just  at  the  time  the  color  is  changing 
from  straw  to  blue.  In 'exceptional  cases,  however,  as  when  chipping 
extra-hard  metal,  the  chisel  may  require  to  be  made  harder,  but  the 
hammer-blows  must  be  correspondingly  light.  Otherwise  the  more 
brittle  edge  will  fail. 

No  matter  how  carefully  the  chisel  may  be  tempered  it  may  be 
softened  in  a  few  minutes  by  overheating  the  edge  at  the  emery-wheel.  To 
avoid  this  a  constant  flow  of  water  must  be  directed  to  the  point  of  the 
chisel  when  grinding  it.  If  the  emery-wheel  have  no  automatic  water- 
supply,  the  chisel  must  be  frequently  dipped  in  a  pail  of  water.  Grinding 
the  temper  from  the  chisel  is  a  common  fault  with  beginners,  and  some- 
times they  botch  their  work  by  attempting  to  use  the  chisels  in  this 
condition. 

When  to  Use  Chisels. — In  general  the  chisel  should  not  be  used  when 
a  machine  is  available  for  the  work,  because  chipping  is  nearly  always 
a  slower  process  than  machining.  The  chisel  may  be  used  to  cut  off 
risers  and  small  irregularities  from  rough  castings;  for  various  odds 
and  ends,  incident  to  the  fitting  of  machine  details  together,  and  espe- 
cially in  emergencies,  or  when  not  within  reach  of  a  machine-shop. 
In  order  to  have  an  ever-ready  and  a  systematic  means  of  imparting 
instruction,  an  instructor  may  require  a  student  to  chip  pieces  which 
would  otherwise  be  machined. 

In  this  chapter  we  have  discussed  the  principal  considerations 
affecting  the  quality  and  quantity  of  work  possible  with  the  chisel. 
Failing  to  be  instructed  in  these  particulars  the  student  will  pay  for 
his  heedlessness  in  the  extra  work  required  in  filing  away  the  irregu- 
larities left  by  the  chisel. 


CHAPTER  IV 
FILES  AND  FILING 

Definition  and  General  Remarks. — A  definition  is  scarcely  neces- 
sary in  this  connection,  but  the  file  may  be  defined  as  a  bar  of  tool-steel 
pointed  at  one  end  to  receive  the  handle,  and  having  cutting  edges 
or  teeth  extending  from  near  the  handle  to  the  opposite  end.  We 
use  the  file  at  the  bench  to  remove  irregularities  left  by  the  chisel,  to 
fit  parts  together,  and  to  smooth  surfaces  preparatory  to  the  polishing 
processes.  The  file  is  used  at  the  lathe  in  fitting,  and  in  preparing 
the  work  for  the  final  finish  with  emery. 

One  of  the  most  difficult  operations  of  the  machine-shop  is  that 
of  filing  a  true  plane.  Take,  for  instance,  a  rectangular  block  having 
a  plane  surface  2"X4".  To  file  this  surface  perfectly  true  is  impossible; 
to  file  it  sufficiently  accurate  to  meet  the  most  exacting  demands  re- 
quires a  high  degree  of  skill.  With  this  in  view  the  beginner  need  not 
get  discouraged  if  his  first  efforts  in  using  the  file  result  in  compara- 
tive failure. 

Classification  of  Files.  Tang,  Pitch,  etc. — There  is  a  bewildering 
array  of  names,  shapes,  and  peculiarities  connected  with  the  subject 
of  files.  Many  of  these  names  with  their  corresponding  sections  are 
shown  in  Figs.  76  and  77.  The  number  adjacent  to  each  section 
gives  the  length  of  that  section,  there  being  as  many  as  fourteen 
different  lengths  and  sectional  areas  under  some  of  the  names.  The 
sections  are  not  shown  full  size;  they  show  the  relative  areas  rather 
than  the  actual. 

Fig.  78  represents  various  cuts,  or  teeth  characteristics,  the  two 
extreme  grades,  " rough"  and  "dead-smooth,"  being  omitted.  Fig.  79 
shows  a  common  flat  file  without  handle. 

The  spike-shaped  end  which  receives  the  handle  is  called  the  tang, 
and  the  part  at  which  the  tang  joins  the  file  proper  is  the  heel.  The 
length  of  a  file  is  measured  from  the  heel  to  the  end  opposite  the  tang. 

44 


FILES  AND  FILING  45 

Notwithstanding  the-  great  variety  of  files  they  may  be  divided 
into  three  general  classes,  viz.,  single-cut,  double-cut,  and  rasps.  These 
again  may  be  subdivided  with  respect  to  the  fineness  of  the  teeth  as 
follows : 


Single-cut  into  rough,  coarse,  bastard,  second-cut,  smooth. 
Double-cut  into  coarse,  bastard,  second-cut,  smooth,  dead-smooth. 
Rasps  into  coarse,  bastard,  second-cut,  smooth. 
Single-cut  files  have  one  series  of  teeth.     Double-cut  have  a  second 
series  cut  diagonally  across  the  first  series.     Files  are  cut  with  a  kmd 


46 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  chisel-edge  tool.  Rasps  are  cut  with  a  pointed  punch.  The  teeth 
of  rasps  are  therefore  disconnected  cutting  points,  rather  than  continuous 
cutting  edges. 


Pitch  of  Teeth  Varies  with  Length  of  File.— The  terms  rough,  coarse, 
bastard,  second-cut,  etc.,  refer  to  the  pitch  of  the  teeth,  or  degree  of  fine- 
ness, the  coarsest  being  about  20  and  the  finest  about  120  to  the  linear 
inch.  It  is  important  to  observe,  however,  that  these  terms  do  not, 
independently  of  the  length  of  the  file,  definitely  express  the  number 
of  teeth  per  inch  for  a  given  file.  They  rather  indicate  the  range  of 


FILES  AND  FILING 


47 


pitches  for  a  given  nominal  cut.     To  definitely  express  the  pitch  the 
length  of  the  file  must  be  coupled  with  the  name  of  the  cut.     Thus 


Rasp  Coarse 


Rasp  Bastard 


Double  Cut  Bastard        Single  Cut  Bastard 


f&G*&GV£$n 
^/^/^v^V^V^ 

C^Jwl 


Rasp  Second  Cut 


Dbl.  Cut  Second  Cut     Single  Cut  Second  Cut 


Rasp  Smooth  Double  Cut  Smooth        Single  Cut  Smooth 


NICHOLSON  FILE   CO. 


FIG.  78. 


when  we  speak  of  the  bastard  file  we  refer  to  a  subclass  of  files  the  pitches 
of  which  vary  within  certain  limits  directly  as  the  length  of  the  file 


FIG.  79. 


varies.  But  when  we  speak  of  a  12"  bastard  we  mean  a  file  having  a 
definite  number  of  teeth  per  lineal  inch.  Fig.  78  shows  different  grades 
of  cuts  as  they  appear  in  12"  files,  and  Fig.  80  indicates  the  difference 


48 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  80. 


in  pitch  due  to  the  difference  in  length  between  the  longest  and  shortest 
files  of  the  same  cut. 

To  avoid  the  confusion  which  has  often  arisen  the  reader  should  note 
that  the  terms  double-cut  and  second-cut  are  not 
synonymous.  He  should  also  remember  that, 
as  distinguished  from  double-cut,  which  refers  to 
a  file  having  two  courses  of  chisel-cuts  crossing 
each  other,  single-cut  means  one  course  of  teeth. 

Classification  of  Files  with  Respect  to  Shape. 
Meaning  of  the  Terms  Taper  and  Blunt. — Me- 
chanics often  refer  to  files  by  names  indicating 
the  form  of  their  cross-sections,  these  names 
being  qualified  by  other  names  indicating  the 

general  contour  of  the  files.  With  this  in  view  the  Nicholson  File 
Company  classify  files  as  follows:  Quadrangular,  Circular,  Triangular, 
and  Miscellaneous.  In  connection  with  this  nomenclature  the  terms 
taper  and  blunt  are  used. 

A  taper  file  is  a  file  smaller  in  cross-section  at  the  point  than  near  the 
tang.  The  taper  applies  to  both  thickness  and  width  and  extends  on  an 
average  about  5/s  the  file's  length.  A  blunt  file  is  uniform  in  sectional 
area  throughout  its  length. 

Quadrangular  Sections. — The  most  important  files  in  these  sections 
are  the  following:  The  flat  file,  mill-file,  and  square  file,  each  of  which 
is  made  either  blunt  or  taper;  the  hand-file  and  the  pillar-file,  each 
made  uniform  in  width  and  tapering  in  thickness;  the  warding-file, 
which  is  made  uniform  in  thickness,  but  much  tapering  in  width;  the 
equaling-file,  made  blunt  only;  the  flat  wood-file  and  flat  wood-rasp, 
both  made  taper. 

Mill-files  are  sometimes  made  with  one  or  both  edges  semicircular. 
The  equaling-file  is  classed  as  blunt,  because  it  is  very  nearly  of  that 
shape,  but  it  is  in  reality  very  slightly  bellied  or  curved. 

Circular  Sections. — Of  these  sections  the  most  important  are  the 
round  and  half-round,  made  either  blunt  or  taper;  the  pitsaw-file,  blunt; 
the  half-round  wood-file,  half-round  wood-rasp,  and  cabinet-file,  made 
taper. 

Triangular  Sections. — As  indicated  by  their  names,  the  files  of  tri- 
angular cross-section  are  used  mainly  for  filing  saws.  Thus  we  have 
the  hand-saw  file,  made  either  blunt  or  taper;  the  slim  hand-saw  or  slim 
tapers;  the  double-ended  hand-saw,  the  three-square,  and  the  knife  or 
knife-edge  files,  made  taper;  the  cant-file  and  the  cant-saw  file,  blunt; 


FILES  AND  FILING  4£ 

and  the  band-saw  file,  made  the  same  as  the  regular  hand-saw,  excepting 
that  the  edges  are  rounded. 

Miscellaneous. — Of  this  class  we  mention  only  the  crossing-file,  made 
either  blunt  or  taper,  and  the  featjier-edge  file,  made  blunt. 

Hand-cut  and  Machine-cut  Fttes.  Increment  Cut. — Formerly  all 
files  were  cut  by  hand,  and  machine-cut  files  had  been  on  the  market 
a.  long  time  before  they  were  regarded  as  serious  competitors  of  the 
older  files.  Notwithstanding  that  the  hand-cut  files  were  slightly 
irregular  in  pitch  they  showed  a  high  degree  of  efficiency  in  operation. 
When  it  was  discovered  that  their  irregularity  was  in  a  large  measure 
the  cause  of  the  high  efficiency,  the  makers  of  machine-cut  files  endeavored 
to  imitate  this  irregularity.  As  a  result  of  such  endeavor  we  have 
the  modern  increment-cut  file.  It  is  difficult  to  detect  any  difference 
between  this  file  and  the  hand-cut. 

Convexity  of  Files. — Convexity  presents  one  of  the  advantages  of 
the  irregularly  spaced  teeth,  viz.,  it  increases  the  bite  of  the  file  by  afford- 
ing a  smaller  area  of  contact.  Convexity  is  advantageous  in  another 
way,  i.e.,  it  compensates  for  the  rocking  motion  of  the  file.  This  rock- 
ing or  curved  movement  of  the  file  must  of  necessity  make  a  convex 
surface  on  the  work  when  a  " blunt"  or  straight-face  file  is  used. 
Indeed  it  requires  considerable  skill  to  file  straight  even  when  a  con- 
vex file  is  used. 

Files  are  more  or  less  bent  during  the  tempering  process.  This 
may  neutralize  the  convexity  on  one  side  and  increase  it  on  the  other. 
By  sighting  along  the  face  of  the  file  one  may  easily  determine  which 
side  is  in  proper  condition  for  filing  a  plane  surface.  The  opposite 
side  of  the  file  may  be  used  for  round  work,  either  at  the  vise  or  while 
the  work  is  in  rotation  in  the  lathe. 

Grasping  the  File.  Cross-filing  and  Draw-filing. — When  heavy 
duty  is  required  of  a  file  a  strong  heavy  file  should  be  -used.  Such  a 


FIG.  81. 


file  should  be  grasped  as  in  Fig.  81,  the  thumb  of  the  right  hand  rest- 
ing on  top  and  the  end  of  the  file-handle  pressing  against  the  palm  of 
the  hand  in  line  with  the  wrist-joint.  This  method  is  correct  also  for  a 


50 


MACHINE-SHOP  TOOLS  AND  METHODS 


somewhat  lighter  file  when  the  pressure  is  not  great  enough  to  seri- 
ously bend  the  file.  But  when  the  file  is  thin  or  likely  to  be  bent  by 
the  pressure  required  to  make  it  cut,  it  should  be  grasped  as  in  Fig.  82. 


FIG.  82. 

By  thus  grasping  the  file  we  may,  by  the  downward  pressure  of  the 
thumb  and  upward  pressure  of  the  fingers,  support  the  file  against  flex- 
ure, which  flexure  would  cause  curvature  of  the  work. 

The  height  of  the  vise  jaws  should  be  about  42"  from  the  floor, 
though  for  the  heaviest  work  it  would  be  better  to  have  the  vise  lower 
if  it  could  be  readjusted  again  to  42",  this  height  being  suitable  for  general 
work.  In  heavy  work  the  workman  should  lean  forward  somewhat, 
using  the  momentum  and  weight  of  the  body  to  aid  in  applying  pres- 
sure on  the  file.  But  in  lighter  filing  he  may  stand  more  erect,  depend- 
ing mainly  on  the  movement  of  his  arms. 

The  above  methods  of  grasping  the  file  hold  good  when  the  strokes 
of  the  file  are  approximately  in  the  direction  of  its  length,  or  endwise. 
This  movement  of  the  file  is  called  cross-filing. 

In  filing  very  light  work  the  file  is  sometimes  held  with  one  hand, 
and  in  special  cases,  as  for  instance  in  filing  the  bore  of  a  long-hub 
pulley,  the  file  may  be  grasped  at  the  handle  end  by  both  hands.  These 
methods  should  also  be  classed  under  cross-filing. 

Draw-filing  is  a  slower  process  than  cross-filing,  but  it  makes  a 
smoother  surface.  In  draw-filing  the  file  is  moved  in  a  path  approxi- 
mately at  right  angles  to  its  length.  Fig.  83  shows  the  method  of 
grasping  the  file.  Unless  the  file  be  of  unusual  length  the  handle  should 
be  removed.  If  the  handle  remain  on  the  file,  it  should  not  be  used 
in  draw-filing.  To  avoid  springing  the  file  it  should  be  grasped  as  close 
to  the  work  as  the  width  of  the  latter  will  permit. 

As  the  face  of  the  file  is  "bellied"  lengthwise,  it  will,  if  moved  in 
one  unchanging  path,  make  a  concave  surface  on  the  work.  To  obvi- 


FILES  AND  FILING  51 

ate  this  the  position  of  the;  file  in  relation  to  the  work  should  be  fre^ 
}uently  changed. 

As  draw-filing  (on  plane  surfaces)  is  used  mainly  to  give  the  final 
finish  preparatory  to  polishing,  the  surface  of  the  work  should  be  filed 
very  nearly  true  with  a  coarser  file  first.  In  some  cases  a  second-cut 
file  would  answer  for  the  draw-filing  process,  but  for  a  finer  finish  the 
smooth  file  would  be  more  satisfactory. 

The  draw-filing  process  is  sometimes  used  on  cylindrical  work,  such 
as  piston-rods,  etc.  The  object  in  such  cases  is  to  lay  the  direction  of 
the  file-marks  parallel  with  the  reciprocating  motion  of  the  rod,  and 


FIG.  83. 

thereby  lessen  the  wear  on  the  rod-packing.  Great  care  is  required  m 
such  work  to  avoid  introducing  irregularities  in  the  surface  being  filed. 
The  lines  of  file  contact  around  the  rod  or  shaft  should  change  in  very 
small  steps,  and  just  sufficient  filing  should  be  done  to  hide  the  lathe- 
tool  marks. 

Safe-edge  Files. — In  filing  work  having  two  plane  surfaces  at  right 
angles,  as  for  instance  the  keyway  in  a  shaft,  it  is  sometimes  necessary  to 
file  one  of  the  surfaces  without  cutting  the  other.  For  this  purpose 
we  use  a  file  having  one  blank  side  or  edge.  Such  files  are  called  safe- 
edge  files,  and  they  may  be  purchased  of  the  dealers.  But  when  one  is 
not  at  hand  it  is  permissible  to  grind  the  teeth  off  one  edge  or  one  side 
of  a  common  file. 

Pinning — Prevention  of.  Definition. — The  term  pinning  means  the 
wedging  of  minute  lumps  of  metal  ("pins")  between  the  teeth  of  the 
file.  It  is  different  from  the  accumulation  of  file-dust.  The  latter 
may  be  brushed  out  with  a  file-brush  or  file-card  made  for  the  purpose 
see  Fig.  84) ;  but  pins  wedged  in  between  the  file-teeth  must  be  removed 
with  a  pointed  instrument.  A  machinist's  scriber  (a  tool  for  drawing 
lines  upon  metal)  will  answer  the  purpose,  as  will  also  a  piece  of  wire,  or 


52  MACHINE-SHOP  TOOLS  AND  METHODS 

a  nail  ground  thin  at  the  point.     If  not  removed,  the  lumps  of  metal 
will  cause  scratches  on  the  surface  being  filed. 

Pinning  may  be  partly  prevented  by  use  of  chalk,  oil,  or  turpentine. 
The  latter  is  the  best.  Any  of  these  substances  may  be  applied  to  either 
the  file  or  the  work,  but  they  should  not  be  used  on  cast  iron  and  brass. 
They  are  advantageous  only  in  filing  fibrous  materials,  such  as  wrought 
iron  and  steel.  Any  liquid,  even  the  moisture  of  the  hand,  causes  cast 
iron  to  glaze,  when  the  file  will  not  "bite"  or  take  hold  so  readily.  For 
this  reason  the  workman  should  not  test  the  smoothness  of  the  filed 
surface  by  rubbing  his  hand  over  it.  The  beginner  is  very  prone  to 


FIG.  84. 

do  this  when  smooth-filing,  as  the  writer  has  often  observed.  A  good 
illustration  of  the  tendency  of  cast  iron  to  glaze  is  that  of  a  piston  work- 
ing in  a  steam-cylinder.  The  moisture  of  the  steam  and  oil  causes  the 
piston-rings  to  take  on  a  glassy  surface  which  is  decidedly  advantageous 
in  resisting  wear  of  these  parts. 

Files  Most  Used  in  the  Machine-shop. — Of  the  files  described  the 
most  common  are  the  flat  file,  half-round  file,  round  file,  square  file, 
and  three-cornered  file.  The  surface  to  be  filed  will  generally  suggest 
the  shape  of  the  file.  For  plane  surfaces  one  would  naturally  use  some 
make  of  flat  file;  for  interior  curves  and  large  round  holes  the  half- 
round  file;  for  small  round  holes  the  round  file;  and  for  slots,  rectangular 
openings,  etc.,  the  flat  file  and  square  file  alternately,  with  perhaps  the 
half-round  file  for  squaring  the  corners.  As  to  the  character  and  cut 
of  the  file,  it  may  be  stated  in  general  terms  that  coarse  and  bastard 
files  are  used  on  common  and  heavy  work,  while  second-cut  and  smooth 
files  are  used  on  finer  work  and  for  finishing  work  started  by  the  coarse 
and  bastard.  When  an  exceptionally  fine  finish  is  required  the  dead- 
smooth  file  may  be  used.  The  rough  file  is  seldom  used.  The  file  tech- 
nically known  as  a  flat  file  is  used  very  extensively  and  for  a  great  variety 
of  work.  It  is  made  double-cut  and  mostly  bastard,  but  may  also  be 
obtained  in  second-cut,  smooth,  and  dead-smooth. 

The  Hand-file,  being  parallel  as  to  width  and  taper  as  to  thickness, 
differs  from  the  flat  file,  which  is  full  taper.  Like  the  flat  file  it  is  double- 


FILES  AND  FILING  53 

cut,  mostly  bastard,  but  it  may  also  be  had  in  second-cut,  smooth,  and 
dead-smooth.  It  is  made  in  lengths  from  4  to  16  inches,  which  are 
also  the  lengths  of  the  flat  file.  The  hand-file  is  of  the  same  form  in 
cross-section  as  the  flat,  the  section ^of  which  is  shown  in  Fig.  76.  The 
hand-file  is  very  generally  used  by  machinists  for  finishing  flat  surfaces, 
and  having  one  safe,  edge  it  may  be  used  in  some  cases  in  which  the 
flat  file  will  not  answer. 

The  Pillar-file  is  nearly  the  same  as  the  hand-file,  but  it  is  narrower. 
It  has  one  safe  edge,  and  in  addition  to  being  adapted  to  finishing  flat 
surfaces  in  general,  it  is  also  made  in  extra-narrow  form,  which  admits 
of  its  being  used  in  narrow  apertures  where  the  hand-file  would  not 
apply.  The  wider  pillar-files  are  made  in  lengths  from  6  to  14  inches. 

The  Mill-file  is  always  single-cut  and  mostly  bastard.  Its  prin- 
cipal use  is  for  sharpening  mill-saws,  mowing-machine  knives  and  plows. 
This  file  has  met  with  much  favor  in  the  machine-shop.  It  is  well 
adapted  to  lathe  work  and  to  draw-filing  at  the  vise.  It  is  also  used 
to  some  extent  for  finishing  the  various  compositions  of  brass  and  bronze. 
In  high-grade  finishing  it  should  be  followed  by  some  file  of  finer  cut 
or  pitch.  The  mill-file  is  made  in  lengths  varying  between  4  and  16 
inches. 

The  Equaling-file  is  made  from  mill  sections,  but  it  is  double-cut 
and  blunt,  mostly  bastard.  It  is  used  for  general  machine-shop  work. 
Length  6  to  12  inches.  Seldom  used. 

The  Round  or  Rat-tail  File  is  double-cut  and  mostly  bastard,  as 
is  also  the  half-round  file.  But  the  latter  is  made  also  in  second-cut, 
smooth,  and  dead-smooth.  Those  made  finer  than  bastard  are  single- 
cut  on  the  convex  side.  Being  made  both  taper  and  blunt,  and  in 
the  above  range  of  pitches,  the  half-round  file  has  a  very  wide  appli- 
cation in  the  machine-shop.  Evidently  it  may  be  used  for  fine  finish- 
ing to  follow  the  mill-file,  and  in  many  kinds  of  work  it  may  be  used 
instead  of  the  flat  file  and  hand-file.  The  round  file,  being  generally 
of  bastard  cut,  is  not  well  adapted  to  any  other  work  than  enlarging 
holes;  but  it  is  sometimes  used  in  smoothing  small  fillets  when  a  half- 
round  file  small  enough  is  not  available.  Both  the  round  and  half- 
round  files  are  made  in  lengths  from  4  to  16  inches. 

The  reader  will  have  observed  that  a  slight  modification  in  the  name 
of  a  file  sometimes  materially  affects  its  character  and  use.  Thus  the 
half-round  wood  file  is  made  only  in  coarse  pitch  and  in  lengths 
from  8  to  14  inches.  It  is  double-cut  and  used  occasionally  on  coarse 
grades  of  brass  work,  as  well  as  for  woodwork  generally. 


54  MACHINE-SHOP  TOOLS  AND  METHODS 

As  previously  stated,  the  files  of  triangular  cross-section  are  used 
mainly  for  filing  saws,  the  name  of  the  file  usually  indicating  the  kind 
of  saw  for  which  the  file  is  adapted.  But  the  three-square  or  three-cornered 
file  cannot  be  used  in  such  work,  for  the  reason  that  the  corners  or  edges 
are  left  sharp  and  uncut.  This  file  is  quite  generally  used  in  the 
machine-shop  for  filing  internal  angles,  for  squaring  the  corners  of 
rectangular  apertures,  key  ways,  etc.,  and  for  filing  taps  and  cutters. 
It  is  double-cut  and  usually  bastard.  Length  6  to  14  inches. 

Finishing  a  Flat  Surface. — If  the  surface  be  rough  as  left  by  the 
chisel,  it  should  first  be  cross-filed  with  a  coarse  or  bastard  file.  During 
this  process  the  direction  of  the  file-strokes  should  be  frequently  changed, 
the  angle  of  the  alternating  strokes  being  unimportant.  The  object 
of  changing  the  strokes  is  twofold:  first,  to  make  the  file  "bite"  more 
freely;  second,  to  show  more  clearly  the  points  of  contact  between 
file  and  surface,  and  thus  enable  the  operator  to  correct  any  tendency 
toward  curvature  in  the  filed  surface.  In  this  connection  refer  to  what 
has  been  said  with  respect  to  convexity  in  files. 

Having  thus  filed  the  work  as  nearly  true  as  practicable,  the  file- 
marks  should  now  be  reduced  with  a  second-cut  or  smooth  file  prepara- 
tory to  draw-filing.  If  the  detail  be  steel  or  wrought  iron,  great  care 
will  be  necessary  during  this  preparatory  work  to  prevent  pinning. 
Draw-filing  being  a  comparatively  slow  process,  too  much  time  will 
be  required  if  deep  scratches  have  been  made  in  cross-filing.  Work 
finished  without  first  obliterating  these  scratches  is  sometimes  sarcas- 
tically referred  to  by  old  mechanics  as  having  "deep  scratches  and 
high  polish."  As  has  been  indicated,  it  may  be  well  to  use  chalk,  oil, 
or  turpentine  at  this  juncture,  if  fibrous  material  is  being  filed. 

For  the  draw-filing  process  a  second-cut,  smooth,  or  dead-smooth 
file  would  be  used.  Sometimes  we  use  two  kinds.  This  method 
will  give  a  better  finish,  or  leave  less  work  to  be  done  with  the  emery- 
paper  or  other  polishing  material.  Assuming  that  a  smooth  file  is  to 
be  used,  the  surface  should  be  gone  over  very  carefully  with  this  file, 
preferably  moving  the  file  crosswise  the  grain  of  the  metal.  During 
this  operation  the  surface  should  be  frequently  tested  with  a  straight- 
edge or  surface  plate.  Chalk  used  to  prevent  pinning  will  be  found 
to  be  more  convenient  and  offer  less  hindrance  to  the  application  of  the 
testing  instrument  than  oil.  The  pinning  and  scratching  are  less  likely 
to  occur  with  short  file-strokes  than  with  long  ones. 

When  the  surface  has  been  made  fairly  true  and  smooth  by  draw- 
filing  it  should  next  be  gone  over  with  emery-cloth,  say  No.  1/2.  The 


FILES  AND  FILING  55 

emery-cloth  may  be  wrapped  around  the  file  or  a  straight  piece  of  wood, 
and  used  the  same  as  in  draw-filing.  The  strokes,  however,  should  be 
at  right  angles  to  those  of  the  latter  process.  Changing  the  strokes 
again  and  using  No.  0  or  00  emery-cloth,  a  still  higher  polish  will  be 
obtained.  Oil  should  be  -used  wim  the  emery-cloth,  both  for  fibrous 
and  non-fibrous  materials,  the  object  being  to  give  a  polish  which  is 
not  so  likely  to  rust. 

By  using  the  smooth  and  dead-smooth  files,  the  strokes  of  the  lat- 
ter being  crosswise  those  of  the  former,  and  following  this  work  with 
0  and  00  emery-cloth  or  crocus-cloth,  which  should  also  be  used  with 
alternately  changing  strokes,  a  finish  may  be  had  which  will  satisfy 
the  most  exacting  requirements. 

It  may  be  observed  that  the  average  polished  surface  is  merely  a  sur- 
face in  which  the  scratches  are  very  fine  and  very  nearly  parallel.  The 
latter  point  is  quite  important.  If  the  polishing-marks  run  in  all  direc- 
tions, the  effect  is  not  pleasing  to  the  eye. 

All  that  has  been  said  with  respect  to  draw-filing  and  polishing  a 
surface  which  had  been  prepared  for  these  processes  by  cross-filing 
will  apply  equally  well  to  a  planed  surface.  But  the  latter  should 
not  require  the  preliminary  work  of  cross-filing.  If,  however,  because 
of  unskillful  manipulation  on  the  planer,  cross-filing  be  required,  nothing 
coarser  than  a  second-cut  file  should  be  tolerated.  It  would  be 
cheaper  to  replane  the  surface  than  consume  too  much  time  with  the 
file. 

Filing  Broad  Surfaces. — In  filing  a  surface  of  such  breadth  that 
the  ordinary  file-handle  would  interfere  with  the  strokes  of  the  file,  a 
special  file-handle  is  employed.  The  best  device  of  this  character 
is  that  shown  in  Fig.  85.  It  is  called  a  surface  file-holder.  The  part 


FIG.  85. 

which  fits  over  the  tang  is  slightly  dovetailed  and  also  tapering,  the 
tang  being  filed  to  correspond.  The  part  at  the  point  of  the  file  is  also 
slightly  undercut.  Both  of  these  pieces  clear  the  surface  of  the  work. 
The  handle  is  threaded  to  fit  the  rod  which  passes  through  the  center 
and  tang  pieces.  By  screwing  up  the  handle  and  adjusting  the  center- 
piece lengthwise,  the  convexity  of  the  file  may  be  increased  at  any  point 
along  its  length. 


56 


MACHINE-SHOP  TOOLS  AND  METHODS 


A  cheaper  and  much  inferior  surface  file-holder  is  shown  in  Fig.  86. 

It  would  be  pertinent  to  inquire,  how  the  draw-filing  process  could 
be  applied  to  broad  surfaces?  In  answer  to  this  question  it  may  be 
stated  that  draw-filing  is  not  used  by  all  mechanics,  even  for  narrow 
work.  In  wide  work  it  would  be  more  convenient  to  use  coarse  emery- 


FIG.  86. 

«loth  on  a  thick  block  of  wood,  finishing  with  the  finer  grades.  It  will, 
however,  require  more  preparatory  work  with  the  smooth  file  when 
emery-cloth  is  used  instead  of  draw-filing. 

Filing  Curved  Surfaces. — If  the  curve  be  exterior  or  convex,  it  will 
be  difficult  to  file  it  without  making  flat  spots.  To  obviate  this  the 
file  must  be  given  a  rocking  or  circular  sweep  around  the  work,  as  illus- 
trated in  Fig.  87.  In  using  emery-cloth,  a  strip  of  suitable  width  should 


\ 


FIG.  $7. 


be  wrapped  partly  around  the  curved  surface,  and  with  one  hand  on 
each  end  the  cloth  it  should  be  wiped  back  and  forth  around  the  work 
in  a  kind  of  seesaw  fashion. 

Another  method  may  be  briefly  given,  as  follows:  Hollow  out  a 
block  of  soft  wood  to  fit  the  curved  surface,  and  after  smearing  the 
surface  or  the  wood  with  oil  and  emery  move  the  block  in  a  circular 
path  back  and  forth  around  the  work  until  the  required  finish  is 
attained. 


STUB    FILES  AND    HOLDER. 
FILES  DETACHABLE. 


FILES  AND  FILING  57 

In  filing  an  interior  curve  like  that  of  a  pulley-bore  the  largest  round 
or  half-round  file  practicable  should  be  used.  The  problem  in  this 
work  is  to  enlarge  or  smooth  the  bore  without  making  a  series  of  small 
curves  lengthwise  the  hole.  To 'obviate  this  the  file  should  be  given 
a  combined  circular  and  longitudinal  motion.  The  file  must  be  kept 
from  rocking  lengthwise;  otherwise  the  hole  will  be  made  larger  at 
the  ends  than  in  the  middle. 

Curving  Files  for  Special  Work. — In  filing  the  shallow  recesses  and 
curves  peculiar  to  ornamental  work — 
stove  patterns,  for  instance — it  may 
be  necessary  to  use  small  stub-files 
such  as  are  shown  in  Fig.  88.  The 
handle  or  holder  shown  in  connec- 
tion with  these  samples  is  soldered 
to  the  stub  and  is  called  a  stub-file 
holder.  In  the  absence  of  such 
files  it  is  permissible  to  bend  an 
ordinary  file  to  the  required  shape. 

Filing  a  Rectangular  Recess. — In  filing  a  rectangular  recess  like  that 
of  a  key-seat  in  a  pulley  the  file  is  very  likely  to  leave  small  fillets  in  the 
two  corners  of  the  recess.  If  the  workman  neglect  to  file  correspond- 
ingly rounded  corners  on  the  detail  which  is  to  fit  the  recess,  the  detail, 
instead  of  fitting  correctly,  will  touch  only  on  the  corners.  The 
writer  has  often  observed  this  fault  in  the  work  of  beginners.  When 
there  is  objection  to  rounding  the  corners  of  the  key  or  other  detail, 
the  small  fillets  (so  small  as  to  be  often  overlooked)  may  be  cut  away 
vrrth  a  fine  half-round  or  three-cornered  file. 

Filing  Lathe  Work. — The  principles  covered  in  the  preceding  para- 
graphs of  this  chapter  apply  with  some  exceptions  to  rotating  work. 
The  first  exception  we  note  is  that  in  general  only  the  finer  cuts  of  files 
should  be  used.  If  there  is  much  metal  to  remove,  it  should  be  turned 
off  with  a  lathe-tool.  We  notice,  secondly,  that  instead  of  using  our 
highest  skill  to  prevent  the  rocking  of  the  file,  it  is  advantageous, 
though  not  essential,  to  give  it  a  slightly  rocking  movement. 

The  grade  or  fineness  of  teeth  of  the  file  should  be  governed  by  the 
quality  of  the  work.  The  smooth-cut  flat  files  or  second-cut  mill-files  are 
suitable  for  general  lathe  work,  the  dead-smooth  file  in  flat,  hand,  or 
half-round  shapes  being  used  in  exceptionally  fine  work.  To  obtain 
the  best  finish  the  file  should  be  moved  at  right  angles  to  the  axis  of 
the  rotating  piece  with  light  uniform  pressure.  Each  successive  stroke 


58  MACHINE-SHOP  TOOLS  AND  METHODS 

should  advance  a  small  fraction  of  an  inch  lengthwise  the  work  until 
the  total  length  is  covered.  In  heavier  filing,  when  such  is  permissible, 
the  strokes  may  be  inclined  to  the  axis,  the  direction  being  changed 
back  and  forth  to  avoid  filing  the  work  in  grooves. 

Inasmuch  as  the  work  is  moving  toward  the  file,  the  novice  concludes 
that  the  file  may  be  held  stationary.  It  is  true  that  the  file-strokes 
may  be  slower  than  in  vise  work,  but  holding  the  file  still  always  causes 
rough  and  botched  work. 

Danger  in  Filing  Rotating  Work. — In  filing  close  to  the  headstock 
of  the  lathe  there  is  danger  of  getting  the  clothing  or  the  file  caught 
hi  the  revolving  chuck-plate  or  lathe-dog.  Here  is  where  the  left- 
handed  man  has  the  advantage.  His  arms  and,  indeed,  his  whole  body 
is  farther  away  from  the  chuck.  We  sometimes  gain  the  same  advantage 
by  running  the  lathe  backward  and  standing  on  the  back  side.  It  is 
occasionally  the  case  that  work  having  some  projecting  part  near  the 
center  of  its  length  must  be  filed.  The  student  is  also  cautioned  against 
this  source  of  danger. 

Speed  of  the  Work  when  Filing  in  the  Lathe. — If  the  work  be 
revolved  too  slowly,  the  effect  will  be  to  file  it  "out  of  round";  if  too 
fast,  the  teeth  of  the  file  will  wear  too  fast.  The  work  should  run 
about  three  times  faster  for  filing  than  for  turning. 

The  inexperienced  and  thoughtless  workman  will  sometimes  run  the 
lathe  the  same  number  or  revolutions  in  filing  a  3"  shaft  as  in  a  shaft 
1"  diameter.  It  should  not  be  forgotten  that  the  cutting  speed  for  a 
given  number  of  revolutions  is  proportional  to  the  diameter.  If  the 
file  heat  up  rapidly,  the  speed  should  be  reduced. 

Polishing  in  the  Lathe. — In  polishing  with  emery-cloth  or  crocus-cloth, 
either  of  these  may  be  wrapped  around  the  revolving  work  and  moved 
back  and  forth  lengthwise  the  work  by  hand.  When  giving  the  final 
polish  No.  0  or  00  cloth  should  be  used.  This  should  be  moved  very 
slowly  along  the  shaft,  the  object  being  to  lay  the  polishing  marks  so 
close  together  and  so  regularly  that  they  will  scarcely  be  discernible. 
Some  mechanics  follow  the  emery-cloth  with  waste  sprinkled  with 
flour-emery.  This  gives  a  very  bright  appearance  to  brasswork,  and 
also  improves  the  looks  of  steel  and  other  metals.  The  waste  is  held 
around  the  shaft  by  the  hand. 

To  obtain  a  quick  polish,  but  generally  not  so  fine  a  finish,  polishing- 
clamps  may  be  used  (see  Fig.  89).  These  may  be  made  of  two  pieces 
of  soft  pine  about  \l/2"  thick X3V2"  wide X 24"  long.  The  pine  sticks 
should  be  hinged  together  at  one  end  with  sole-leather.  The  opposite  ends 


FILES  AND   FILING  59 

should  be  trimmed  with  a  draw-shave  to  make  them  more  comfortable 
to  the  hands.  About  3"  from  the  hinged  ends  emery  and  oil  may  be 
applied  to  the  inner  sides  of  the  sticks.  Now  grip  the  revolving  shaft 
or  other  detail  between  the  clamps,  and  while  applying  pressure  to  the 
ends  intended  for  the  hands,  movAhe  clamps  back  and  forth  lengthwise 
the  shaft  until  a  satisfactory  polish  is  obtained.  Oil  should  be  used 
in  connection  with  the  polishing  materials,  excepting  possibly  the  waste. 


FIG.  89. 

The  File  should  not  be  Lifted. — The  file  should  be  held  to  the  work 
during  both  forward  and  return  strokes.  This  applies  to  vise  work  as 
well  as  lathe  work.  On  the  return  stroke  the  pressure  should  be  relieved 
and  the  file  moved  back  quickly  without  cutting. 

Care  of  Files.  Cases  in  which  New  Files  should  not  be  Used. — The 
teeth  of  files  are  very  brittle  and  easily  broken,  especially  when  the  files 
are  new.  For  this  reason  files  should  not  be  promiscuously  mixed  with 
other  metal  tools.  They  should  be  kept  in  some  kind  of  rack  or  parti- 
tioned space,  so  that  they  cannot  touch  each  other.  For  similar  reasons 
a  new  file  should  not  be  used  on  a  casting  just  from  the  foundry;  that 
is,  it  should  not  be  used  to  file  the  scale  of  such  a  casting,  nor  on  a  welded 
joint,  nor  on  the  edge  of  sheet  metal,  nor  on  a  freshly  chipped  surface.  In 
all  such  cases  a  second-hand  or  discarded  file  should  first  be  used.  In. 
filing  a  chipped  surface  the  projections  may  be  flattened  somewhat  with 
the  edge  of  a  new  file,  if  a  second-hand  file  is  not  available.  The  teeth 
on  the  edge  are  not  so  easily  broken,  nor  is  this  part  of  the  file  so  much 
used  as  the  face. 

An  old  file  does  not  readily  take  hold  of  brass  and  cast  iron,  and  it 
is  proper  to  start  the  new  file  on  these  and  other  cast  metals,  excepting 
chipped  surfaces.  After  the  extreme  points  of  the  teeth  are  dulled 
somewhat  the  file  may  be  used  on  the  fibrous  materials,  such  as  steel  and 
wrought  iron. 

Oil  may  be  removed  from  a  file  by  filling  the  teeth  with  chalk,  and 
then  brushing  the  chalk  out  with  a  file-brush.  The  process  may  need 
to  be  repeated  two  or  three  times. 


CHAPTER  V 
THE  SURFACE-PLATE  AND  SCRAPER 

Object  of  the  Surface-plate.  —  A  skilled  workman  can  machine  a 
plane  surface  so  nearly  true  that  it  will  be  difficult  to  detect  any  error 
in  the  surface  with  a  straight-edge,*  and  the  work  will  be  sufficiently 
accurate  for  most  practical  requirements.  Nevertheless  there  will  be 
minute  errors  in  the  surface  which  make  it  unsatisfactory  for  some  pur- 
poses. The  sliding  surfaces  of  machine-tools,  for  instance,  require  to  be 
more  accurate  than  it  is  possible  to  make  them  by  machinery.  For 
detecting  the  minute  errors  a  surface-plate  is  used. 

Description  of  the  Surface-plate.  —  The  surface-plate  is  a  cast-iron 
plate  having  one  surface  which  is  a  practically  perfect  plane.  Fig.  90 


shows  two  surface-plates  of  the  usual  form.  In  this  design  they  are 
made  in  sizes  varying  between  31/2//X4//  and  36"X68",  the  largest  weigh- 
ing more  than  1000  Ibs. 

A  surface-plate  of  large  size  should  be  very  carefully  and  intelli- 
gently designed.  The  metal  should  be  so  distributed  as  to  require  the 
least  weight  consistent  with  accuracy.  The  plate  should  also  be  so 
designed  that  it  would  not  be  distorted  by  variations  in  temperature. 
When  not  in  use  the  plate  should  be  oiled  to  prevent  rusting  and  kept 
in  a  wooden  case. 


*  A  kind  of  ruler  for  testing  plane  surfaces. 

60 


THE  SURFACE-PLATE  AND  SCRAPER  61 

Using  the  Surface-plate. — In  using  the  surface-plate  a  very  thin 
coat  of  Venetian  red,  or  red  lead  mixed  with  oil,  is  applied  to  the  plate 
(preferably  by  hand).  The  pla1;e  "is  then  moved  back  and  forth  over 
the  work,  or  the  work  over  the  glate,  when  the  prominent  spots  on 
the  work  surface  will  be  marked  with  the  coating.  These  spots  are 
to  be  removed  with  the  scraper,  or  scraper  and  file.  It  will  depend 
on  how  nearly  true  the  surface  has  been  machined  as  to  whether  a  file 
will  be  needed,  but  usually  it  will  save  time  to  file  away  most  of  the 
inequalities. 

A  Typical  Scraper. — The  illustrations  in  Fig.  91  show  two  views 
of  a  typical  hand-scraper.  It  is  shaped  very  much  the  same  as  a  common 
file  and  it  is  often  made  from  a  high-grade  thin  file.  It  should  be  forged 
down  to  about  y16"  at  the  point  and  tapered  back  about  I1/ 2"  to  the 


FIG.  91. 

normal  thickness  at  B,  which  thickness  may  be  about  3/i6".  The 
width  at  the  point  may  be  about  Vs".  The  end  A  should  be  ground 
at  right  angles  to  the  center  line.  Looking  at  the  other  view,  the  end 
should  be  slightly  rounded  as  at  D.  If  not  thus  rounded,  the  corners  are 
likely  to  dig  in  and  score  the  work. 

False  Economy  in  Making  a  Scraper  of  Cheap  Steel. — Whether 
forged  from  a  file  or  otherwise  the  scraper  should  be  made  of  a  high 
grade  of  steel,  and  very  carefully  tempered  and  oil-stoned.  As  it  is 
not  subjected  to  hammer-blows,  the  scraper  will  stand  a  much  harder 
temper  than  a  chisel.  Steel  makers  and  dealers  are  always  glad  to 
assist  purchasers  in  selecting  the  grade  of  steel  best  adapted  to  any 
given  purpose,  and  any  effort  at  economy  in  the  price  of  scraper-steel  is 
likely  to  be  more  than  offset  in  the  time  spent  in  grinding  the  scraper. 

A  Double-end  Scraper. — The  scraper  shown  in  Fig.  91  requires  a 
handle  of  the  same  shape  as  a  file-handle.  The  total  length  of  handle 
and  scraper  when  the  scraper  is  new  may  be  9  to  11  inches.  But  scrapers 
are  often  made  double,  so  as  to  cut  on  both  ends.  This  design  is  illus- 
trated in  Fig.  92.  The  thickness  and  width  may  be  about  the  same 
as  that  of  Fig.  91.  As  to  the  length,  some  mechanics  prefer  to  have 
these  scrapers  made  long  enough  to  be  gripped  by  both  hands  with- 


62 


MACHINE-SHOP  TOOLS  AND  METHODS 


out  the  right  hand  touching  the  unprotected  end.  The  writer  has  not 
found  this  extra  length  necessary.  If  the  scraper  be  made  about  10" 
long,  and  the  upper  end  be  covered  with  a  small  leather,  wooden,  or 
lead  socket,  it  will  give  no  trouble.  Waste  is  sometimes  used  for  this 
purpose.  The  curved  shape  at  the  middle  of  this  scraper  is  more  orna- 
mental than  useful.  Unless  the  scraper  be  made  quite  long  and  grasped 
in  the  middle,  the  curves  may  be  omitted. 


FIG.  93. 


FIG.  92. 


Hooked  Form  of  Scraper. — Fig.  93  shows  the  hooked  scraper,  which 
is  preferred  by  some  workmen  for  very  fine  and  smooth  scraping.  The 
fact  that  this  scraper  has  but  one  cutting  edge,  and  therefore  requires 
twice  the  oil-stoning  and  twice  the  number  of  visits  to  the  emery- 
grinder,  is  sufficient  to  offset  any  other  advantages  imaginary  or  real 
it  may  possess. 

Grasping  the  Scraper. — The  "orthodox"  method  of  grasping  the 
scraper  is  shown  in  Fig.  94.  It  is  used  like  the  file,  in  that  the  pressure 


FIG 


should  be  applied  during  the  forward  stroke  and  relieved  on  the  return. 
Drawing  the  Temper  in  Grinding. — It  sometimes  occurs  that  a 
scraper  will  cut  all  right  one  day  but  fail  the  next,  and  the  student  will 
wonder  what  the  trouble  is.  In  most  cases  it  will  be  found  that  the 
iemper  has  been  neutralized  by  allowing  the  point  of  the  scraper  to  become 


THE  SURFACE-PLATE  AND  SCRAPER  63 

heated  in  grinding.  The-  same  precautions  are  necessary  as  were  advised 
with  respect  to  the  chisel. 

Causes  of  Chattering. — When  a  cutting-tool  makes  a  surface  having 
minute  irregularities  of  a  wavy  appearance  it  is  said  to  chatter.  If  a 
scraper  like  Fig.  91  be  ground  so^that  the  end  A  vary  much  from  right 
angles  with  the  center  line,  one  edge  will  be  sharper  than  the  other, 
but  the  sharper  edge  will  be  likely  to  cause  chattering.  Chattering  is 
likely  to  occur,  also,  when  a  tool  has  too  broad  a  bearing  on  the  work. 
The  scraper  should  be  held  at  an  acute  angle  with  the  work  surface. 
If  held  too  high,  it  will  chatter.  When  necessary  to  hold  it  thus  in 
order  to  make  it  cut,  it  should  be  sharpened. 

Moving  the  scraper  in  one  unchanging  direction  will  also  cause  chatter- 
ing. The  proper  method  after  first  testing  with  surface-plate  is  to  go  over 
the  work  in  short  strokes  of  about  1/2  to  7/g  inch  in  one  direction,  and 
then  apply  the  surface-plate  again.  Using  the  scraper  the  second  time, 
it  should  be  moved  at  right  angles  to  the  last  strokes.  The  third  appli- 
cation of  the  scraper  may  be  in  the  same  direction  as  the  first,  or  mid- 
way between  the  angles  of  first  and  second.  Continuing  thus  with  sur- 
face-plate and  scraper,  the  surface  when  completed  will  present  a  very 
pleasing  appearance.  An  expert  workman  can  by  varying  the  direction 
of  scraper-strokes  produce  various  effects,  somewhat  resembling  checker- 
board  work. 

Precautions  Against  Wasting  Time. — It  is  important  to  observe  that 
when  the  surface-plate  is  first  applied  and  touches  only  in  a  few  spots 
the  scraper  should  be  used  quite  vigorously.  As  the  surface  approaches  a 
true  plane  we  use  thinner  coats  of  lead  and  apply  the  scraper  more  lightly, 
taking  care  to  confine  the  scraping  to  the  exact  points  of  contact.  Scraping 
is  a  very  slow  process  at  best,  and  if  we  scrape  too  lightly  at  first,  when 
there  is  considerable  metal  to  remove,  it  may  take  very  much  longer  than 
necessary  to  do  the  work.  The  surface  is  considered  sufficiently  accurate 
for  average  requirements  when  it  is  marked  all  over  in  spots  of  Vs  to 
3/s  inch  apart. 

The  work  should  be  kept  scrupulously  free  from  particles  of  grit 
when  using  the  surface-plate.  An  old  cotton  rag  is  better  than  waste 
for  this  purpose. 

Scrapers  for  Interior  Curves. — The  scrapers  mentioned  above  may 
be  used  on  convex  as  well  as  plane  surfaces.  For  a  concave  surface 
they  cannot  be  used  advantageously.  However,  some  mechanics 
manage  to  use  these  scrapers  to  a  limited  extent  in  scraping  at  right 
angles  to  the  axis  in  a  half -box  bearing.  A  better  scraper  for  the  latter 


64 


MACHINE-SHOP  TOOLS  AND  METHODS 


purpose  is  frequently  made  of  a  three-cornered  file.  Select  such  a  file 
6  or  8  inches  long  and  grind  the  teeth  off,  making  it  quite  pointed  like 
Fig.  95.  It  should  be  used  with  a  file-handle  and  grasped  with  both 


FIG.  95. 

hands  at  the  handle  end.  This  scraper  should  cut  on  its  side  edges,  the 
strokes  being  at  right  angles  to  its  length. 

A  scraper  for  the  same  purpose  may  be  made  of  a  half-round  file. 
The  teeth  should  be  ground  off  and  the  scraper  moved  at  right  angles 
to  its  length,  as  in  the  previous  case.  These  scrapers  should  also  be 
used  with  strokes  at  right  angles  to  the  axis  of  the  bearing.  A  half- 
round  file  ground  on  its  end  may  be  used  to  scrape  lengthwise  the  axis  of 
a  bearing.  It  will  be  understood  that  the  purpose  of  scraping  a  bearing 
is  to  bring  it  to  a  fit  with  its  shaft. 

Special  Form  of  Scraper. — Fig.  96  shows  a  special  form  of  scraper 
sometimes  used  in  scraping  broad  surfaces.  The  blade  is  several  times 


FIG. 


wider  than  in  the  common  scraper,  and  to  avoid  chattering  it  is  used 
with  a  draw-stroke;  that  is  to  say,  it  cuts  while  being  drawn  toward  the 
operator.  The  cut  shows  a  tool  for  scraping  wood,  but  by  using  the 
proper  quality  of  steel  in  the  blade  it  may  be,  and  is,  used  in  the  machine- 
shop  for  metal- work. 


THE  SURFACE-PLATE  AND  SCRAPER  65 

A  home-made  scraper  of  this  kind  may  be  improvised  by  inserting  a 
section  of  file  with  teeth  ground  off,  in  a  slot  milled  lengthwise  a  piece  of 
7/8"  round  steel.  A  3/8~  or  y2-inch  rod  driven  into  a  hole  drilled  in  the 
round  steel  and  sharpened  on  opposite  end  to  fit  a  file-handle  com- 
pletes the  scraper.  The  angle  formed  by  the  rod  and  blade  should  be  at 
least  100°.  These  scrapers  are  not  adapted  to  fine  fitting,  such  as  lathe- 
rests,  etc. 

Using  Emery-cloth  in  Connection  with  the  Scraper. — Emery-paper 
is  used  by  some  workmen  for  the  finishing  touches  on  a  scraped  sur- 
face. A  stick  of  hard  wood  is  whittled  to  about  l/4f  or  3/8//  square 
at  point,  and  the  finest  emery-cloth  wrapped  around  this  point.  The 
stick  is  applied  to  the  work  just  the  same  as  the  scraper  of  Fig.  91. 

Ornamental  Finish  with  Emery. — Small  work  is  sometimes  orna- 
mented at  the  shops  of  the  Michigan  Agricultural  College  (the  writer  is 
not  aware  as  to  whether  this  process  is  used  in  other  shops)  as  follows: 
A  stick  of  wood  is  fitted  to  the  chuck  of  the  sensitive  drill,  and  flour- 
emery  and  oil  are  applied  to  the  work  or  to  the  lower  end  of  the  stick, 
which  should  be  about  Vie"  diameter  and  cut  off  square.  Now,  placing 
the  work  upon  the  drill-platen,  the  revolving  stick  is  brought  to  bear 
very  lightly  upon  the  surface.  The  stick  is  next  lifted  by  the  lever  and 
the  work  moved  about  Vie"  and  the  second  spot  polished.  This  process 
is  repeated  until  the  surface  is  covered  with  the  circular  spots,  the 
direction  of  these  spots  with  respect  to  the  sides  of  the  work  being  regu- 
lated to  suit  the  fancy.  The  surface  to  be  ornamented  should  be  given 
a  flat  polish  with  emery-paper  or  crocus-cloth  preceding  the  ornamental 
finish,  and  during  the  latter  the  drilling-machine  should  run  at  its 
highest  speed.  The  contact  of  the  revolving  stick  should,  as  stated, 
be  very  light;  otherwise  it  will  make  appreciable  indentations  in  the 
work. 

This  ornamental  finish  may  be  made  at  the  bench  by  using  a  breast- 
drill.  The  writer  has  also  produced  various  ornamental  effects  by  going 
over  a  polished  surface  with  emery-paper  wrapped  around  a  stick,  the 
latter  being  moved  in  a  curling  or  wavy  path. 

Using  the  Scraper  at  the  Lathe. — In  lathe  work  the  scraper  is  sup- 
ported upon  a  rest  very  much  the  same  as  the  chisel  is  supported  in 
wood-turning.  The  scraper  shown  in  Fig.  91  is  adaped  to  lathe  work 
as  well  as  vise  work.  In  order  to  approach  the  face-plate  or  a  lathe- 
dog  more  conveniently  it  is  sometimes  ground  to  an  angle,  as  at  A  in 
Fig.  97.  This  scraper  can  be  used  for  smoothing  plain  cylinders,  such 
as  cast-iron  pulleys,  etc.,  and  also  radial-face  work.  It  may  be  used 


66 


MACHINE-SHOP  TOOLS  AND  METHODS 


on  similar  surfaces  in  brass.  Scrapers  are  used  with  greater  advantage, 
however,  on  lathe  work  of  irregular  contour,  ornamental  work,  filleting, 
•etc.  On  work  of  this  character  the  cutting  end  or  point  of  the  scraper  is 
made  in  various  shapes  to  suit  the  required  curve.  The  most  common 
are  semicircular  on  the  end,  and  the  shop  in  which  scrapers  are  much 
used  may  have  these  of  radii  varying  from  1/8  to  3/4  inch. 

In  Fig.  97  at  B  is  shown  a  scraper  as  applied  in  smoothing  out  a 
fillet.  If  the  plain  face  between  the  fillets  has  been  previously  brought 

to  its  final  finish,  some  skill  will 
be  required  to  avoid  cutting  into 
this  plain  face.  For  the  finishing 
touches  in  the  fillet  the  scraper 
should  be  brought  up  to  the  work, 
as  at  B  in  Fig.  98,  and  while  barely 
missing  the  plain  surface  it  should 
be  steadily  advanced  into  the 
fillet.  During  this  operation  the 
forefinger  of  the  right  hand,  being 
under  the  scraper  at  the  dot  Ft 
and  in  contact  with  the  rest  R, 
prevents  the  scraper  from  digging 
into  the  face  while  it  is  moved 
toward  the  fillet.  At  this  time 
the  thumb  of  the  right  hand  is  on  top  of  the  scraper  at  dot  F,  while 
the  left  hand  supports  the  other  end  of  the  scraper.  This  may  appear 
to  be  a  sort  of  left-handed  operation,  but  where  the  conditions  favor 
it  the  position  of  the  two  hands  may  be  reversed.  Of  course  it  will 
be  unnecessary  to  observe  any  cast-iron  rules  in  these  small  matters, 
but  the  beginner  generally  needs  some  definite  directions  to  start  with, 
and  later  he  may  adopt  such  minor  modifications  as  suit  his  convenience, 
the  main  consideration  being  to  get  results. 

It  will  be  noticed  that  the  rest  R  is  quite  close  to  the  work.  This 
is  important,  and  such  rests  may  be  forged  to  suit  various  shapes  of 
work.  Moving  the  rest  too  far  from  the  work  is  likely  to  cause  chatter- 
ing.  Chattering  may  sometimes  be  prevented  by  placing  a  piece  of 
leather  or  other  such  material  between  the  scraper  and  the  rest.  At 
other  times  it  is  necessary  to  lessen  the  line  of  contact  of  scraper  with 
the  work.  In  fillets  and  curved  work  generally,  the  experienced  work- 
man will  vary  the  point  of  contact  by  gently  moving  the  handle  end 
of  the  scraper  in  an  arc  of  a  circle. 


FIG.  97. 


FIG.  98. 


THE  SURFACE-PLATE  AND  SCRAPER  67 

A  scraper  shaped  liked  C,  Fig.  97,  may  be  used  for  the  fillets  and 
also  for  the  flat  surface  between  tne  fillets. 

The  scraper  is  not  used  nearly  so  much  in  modern  practice,  except 
by  amateurs,  as  it  was  fifty  yegrs  ago.  Curved  surfaces  are  shaped 
very  largely  by  special  tools  called  forming-tools.  These  tools  are  made 
with  cutting  edges  of  the  same  shape  as  the  curve. 

The  Graver. — If  we  take  a  square  file  about  8"  long  and  grind  the 
teeth  off  and  then  grind  the  end  to  an  angle  of  about  45°,  we  shall  have 
a  graver.  Gravers  and  other  hand-tools,  formerly  used  to  a  considerable 
extent  on  wrought  iron  and  steel  work,  are  gradually  being  superseded 
by  more  modern  appliances. 

The  cutting  edge  of  a  scraper,  whether  used  at  the  vise  or  lathe, 
should  be  moistened  with  water  or  oil  when  scraping  wrought  iron  and 
«teel. 

Generally  the  scraper  when  used  in  the  lathe  should  be  followed  by 
•emery-cloth,  or  a  file  and  then  emery-cloth. 

All  such  tools  as  scrapers,  files,  etc.,  used  on  rotating  work  should 
have  handles.  Otherwise  if  the  tool  get  caught  or  struck  by  the  work, 
its  pointed  tang  may  be  forced  into  the  flesh  of  the  operator. 

Scrapers  need  to  be  oil-stoned  often.  A  scraper  like  that  shown  in 
Fig.  91  should  be  stoned  mainly  on  the  end,  the  scraper  being  held  per- 
pendicular to  the  stone  and  moved  in  a  circular  path.  The  scraper  may 
also  be  stoned  on  the  two  faces.  Oil  should  be  used  on  the  stone,  but 
the  latter  should  not  be  allowed  to  become  gummy. 


CHAPTER  VI. 


THE  VISE  AND  SOME  VISE  ACCESSORIES 

IN  the  five  preceding  chapters  we  have  dealt  very  largely  with  tools 
and  methods  connected  with  vise  work.     It  is  proper  to  give  some 

attention  to  the  vise  itself.  There  are 
a  great  many  kinds  of  vises  in  use, 
and  inventors  have  exercised  consider- 
able ingenuity  in  the  endeavor  to  com- 
bine in  one  vise  the  good  features  of 
all.  The  problem  is  in  part  a  com- 
mercial one;  the  new  vise  should  cost 
but  little  more  than  the  simpler 
patterns. 

The  Solid-box  Vise.— Fig.  99  shows 
a  vise  which  is  familiar  to  all.  It  is 
one  of  the  older  styles,  which  was 
doubtless  used  by  the  "  village  black- 
smith" whom  Longfellow  has  immor- 
talized. This  vise  still  holds  its  place 
among  its  more  modern  competitors, 
its  merit  being  strength  and  rigidity, 
due  to  its  having  a  support  on  the 
floor  as  well  as  on  the  bench.  The 
objection  against  the  vise,  that  its 
jaws  are  not  parallel  in  vertical  planes 
when  opened  wide,  has  been  overcome 
by  providing  a  second  screw  below  the 
main  screw.  This  second  screw  is 
connected  with  the  main  screw  by 

sprocket-chain  and  wheels,   and  its  operation  will  be  understood  by 
every  boy  who    has    fallen  off   a    bicycle.      The   vise    shown   in   the 

68 


FIG.  99. 


THE  VISE  AND  SOME  VISE  ACCESSORIES 


69 


illustration  is  known  as  the  solid-box  vise.     It  is  not  provided  with  the 
sprocket-chain  arrangement. 

Parallel  Vise. — The  manufacturer  of  the  vise  shown  in  Fig.  100 
has  been  pleased  to  call  it  tha  "Bulldog"    parallel  vise.     The   latter 


FIG.  100. 


half  of  the  designation,  however,  is  the  technical  term  for  vises  of  this 
character.  Parallel  vises  of  the  cheaper  designs  open  by  lever  and 
screw  on  the  same  principle  as  that  of  Fig.  99. 

Parallel  Swivel  Vise. — When  the  vise  of  Fig.  100  is  made  to  swivel 
on  its  base  it  is  called  a  parallel  swivel  vise.     Fig.  101  shows  this  style. 


FIG.  101. 


The  advantage  of  being  able  to  swing  the  work  to  any  angle  in  a  hori- 
zontal plane  will  appeal  to  every  experienced  mechanic. 

In  Fig.  102  we  have  a  vise  which  swivels  on  its  base  and  which  also 


70 


MACHINE-SHOP  TOOLS  AND  METHODS 


has  one  swivel  jaw.    This  latter  provision  is  very  convenient  in  gripping: 
tapering  work. 


FIG.  102 

Combination  pe-vise. — A  shop  in  which  a  limited  amount  of  steam- 
fitting  is  likely  4  je  done  must  have  at  least  one  vise  adapted  to  this 
work.  The  "&  /el  combination  pipe-vise"  of  Fig.  103  can  be  used 


FIG.  103. 

for  pipe  as  well  as  for  general  work.     To  facilitate  threading  pipe  with 
dies  this  vise  should  be  placed  at  the  end  of  the  bench. 

Quick-acting  Vise. — There  is  a  class  of  vises  on  the  market  known 
as  "quick-acting"  or  " rapid"  vises.  Some  of  these  are  " fearfully  and 
wonderfully  made."  The  quick  closing  of  the  jaws  is,  of  course,  desir- 
able, but  this  feature  should  not  be  obtained  at  the  expense  of  durability 
and  solidity.  In  selecting  such  a  vise  one  should  choose  a  design  which 
has  the  least  number  of  parts  consistent  with  the  necessities  of  the  case. 


THE  VISE  AND  SOME  VISE  ACCESSORIES 


71 


Universal  Vise. — In  Fig.  104  is  shown  the  "Emmert  Universal  Vise." 
The  writer  has  not  examined  this  design,  but  the  manufacturers  say: 
"It  will  turn  in  any  position  and  hold  work  so  that  you  can  work  natu- 
rally, without  bending  or  twisting  the  body." 


FIG.  104. 

Hand-  and  Pin-vises. — The  hand-vise  is  a  very  convenient  adjunct 
to  the  stationary  vise.  Fig.  105  shows  one  of  typical  design.  It  is 
used  in  filing  pins  and  small  pieces  which  require  more  delicate  manipu- 
lation than  is  possible  with  the  large  vise. 


The    pin-vise  is  used  almost  exclusively  for  pins  and  other  small 
cylindrical  details.     The  style  shown  in  Fig.  106  is  constructed  on  the 


s       A 

FIG.  106. 

same  principle  as  a  certain  class  of  lathe-chucks.  The  internally  threaded 
and  tapered  sleeve  S  screws  on  the  end  of  A,  which  is  threaded  and  tapered 
to  fit  S.  A  is  drilled  and  sawed  about  one  fourth  its  length  as  shown, 
and  tightening  or  screwing  up  S  causes  the  four  jaws  to  close  and  grip 
a  pin  or  other  detail  placed  in  the  drilled  hole. 


72  MACHINE-SHOP  TOOLS  AND  METHODS 

In  filing  such  work  as  small  pins  in  the  pin-vise,  the  latter  is  held 
in  the  left  hand,  and  the  end  of  the  pin  is  supported  on  top  of  the  sta- 
tionary vise,  or  between  its  jaws,  which  are  opened  about  two  thirds 
the  diameter  of  the  pin.  The  pin  is  rotated  back  and  forth  by  a  move- 
ment of  the  wrist,  and  a  small  file  is  applied  during  the  backward  motion. 
Vise-jaws  with  Detachable  Faces. — The  best  designs  of  stationary 
vises  have  detachable  steel  faces  on  the  jaws.  These  faces  are  serrated 
or  notched  somewhat  like  a  double-cut  file,  the  object  being  to  more 
securely  hold  work  subjected  to  heavy  chipping,  etc.  They  are  made 
detachable  in  order  that  the  manufacturer  may  duplicate  the  faces 
instead  of  the  whole  vise  in  case  of  breakage. 

Vise-clamps. — In  gripping  rough  castings,  forgings,  etc.,  the  steel 
faces  mentioned  are  brought  into  direct  contact  with  the  work.  But 
to  avoid  marring  finished  work,  vise-clamps  are  interposed  between 
the  work  and  the  steel  faces.  Copper  clamps  are  used  more  than  any 
other  kind  for  this  purpose.  Sheet  copper  about  Vie"  thick  will 
answer.  Cut  out  two  pieces,  each  equal  in  width  to  the  vise-jaws  and 
about  3"  long.  Heat  them  red-hot  and  cool  in  water.  This  will  anneal 
or  soften  the  copper.  Clamp  the  two  pieces  tightly  in  the  vise  with 
the  lower  edges  even  with  the  lower  edges  of  the  vise-jaws.  Separate 
them  at  the  top  and  bend  each  over  its  vise-jaw,  hammering  the  pieces 
down  to  closely  fit  the  upper  surface  of  the  vise- jaws. 

In  order  to  grip  thin  work,  the  upper  edges  of  the  clamps  answering  to 
the  upper  edges  of  the  vise-jaws  should  be  square  and  sharply  defined. 
If  not  satisfactory  in  this  respect,  heat  and  pound  down  (after  cooling) 
the  copper  pieces  again,  giving  special  attention  to  the  upper  edges. 

The  usage  to  which  the  clamps  are  subjected  tends  to  harden  them. 
For  this  reason  they  should  occasionally  be  reannealed. 

Lead  Clamps. — Lead  clamps  are  very  desirable  for   gripping   small 

pieces  which,  because  of  their  limit- 
ed contact,  are  more  likely  to  be 
slightly  bruised  or  mashed.  With 
lead  clamps  a  screw  may  be  held  in 
the  vise  without  spoiling  the  thread. 
Fig.  107  shows  one  of  these  clamps 
and  a  mold  for  making  them. 
FlG-  107'  Both  the  lead  and  copper 

clamps  are  likely  to  become  imbedded  with  grit  and  small  particles  of 
steel.  On  this  account  some  mechanics  use  leather  clamps  for  very 
highly  polished  and  delicate  work.  To  make  these  clamps,  cut  out 


THE  VISE  AND  SOME  VISE  ACCESSORIES  73 

two  pieces  of  leather  of  the  right  size,  and  cut  them  half-way  through 
on  the  line  where  they  are  bent  over  the  vise-jaws 

Another  Method  of  Holdingj  Screws. — A  threaded  bolt  or  similar 
detail  may  be  held  in  the  vise  without  clamps  by  screwing  the  thread 
into  a  nut  which  has  been  sawed  through  on  one  side.  The  pressure 
of  the  vise-jaws  will  cause  the  nut  to  tightly  grip  the  thread  without 
injuring  it. 

The  Hack-saw. — The  novice  sometimes  expresses  surprise  that  the 
mechanic  can  "saw  metal  as  he  saws  wood."  Fearing,  therefore,  that 
this  handy  tool  may  be  overlooked  by  the  beginner  hi  purchasing  his 
"kit,"  we  shall  mention  it  in  this  connection.  The  hack-saw  frame 
shown  in  Fig.  108  will  take  blades  from  6  to  12  inches  in  length,  and 


FIG.  108. 

it  will  hold  the  blades  in  four  different  angles  with  respect  to  the  frame. 
Formerly  hack-saw  blades  were  made  to  be  filed  like  a  carpenter's  saw, 
but  these  have  been  very  generally  superseded  by  the  tempered  blades. 
The  latter  are  too  hard  to  be  filed  and  too  cheap  to  make  it  pay  to  file 
them.  The  average  length  can  be  purchased  for  about  70  cents  per 
dozen.  After  one  has  become  accustomed  to  the  use  of  a  hack-saw  he 
regards  it  as  an  almost  indispensable  tool  in  connection  with  vise  work. 
Pliers.  —This  is  another  very  useful  tool;  but  there  are  so  many 
different  designs  that  it  is  difficult  to  settle  upon  an  illustration.  Fig.  109 


FIG.  109. 


shows  a  tool  which  suits  the  proverbial  "jack-at-all-trades."  It  com- 
bines in  a  small  compass  flat-nose  pliers,  gas-pliers,  wire-cutter,  and 
screw-driver.  "By  a  quarter-turn  of  the  handle,  and  sliding  it  from 
one  hole  to  the  other,  it  changes  from  the  size  of  a  gas-burner  to  3/4r/ 
pipe,  or  from  Vie"  to  1  inch  round  or  square.", 


CHAPTER  VII 
DRILLING-MACHINES 

Ratchet-drills. — The  term  drill,  which  primarily  means  a  tool  for 
originating  and  enlarging  holes,  is  oft^n  used  to  denote  the  machine 
by  which  the  tool  is  driven.  Thus  we  have  sensitive  drills,  radial  drills, 
gang  drills,  etc.,  all  of  which  machines  are  described  in  this  chapter. 


FIG.  110. 


The  simplest  form  of  drilling-machine  is  the  ratchet-drill.  This,  in 
connection  with  its  brace,  is  shown  in  Fig.  110.  The  device  marked  D 
is  the  ratchet-drill,  the  brace,  which  is  called  the  "old  man/'  being 
lettered  0.  C,  D  1,  and  W  represent  respectively  a  clamp  for  holding 

74 


DRILLING-MACHINES  75 

the  brace,  the  drill,  and  the  work.  This  ratchet-drill  is  operated  by 
hand  by  means  of  the  lever  L,  anpl  is  fed  to  the  work  by  frequent  slight 
movements  of  the  small  rod  R.  R  turns  a  small  screw  which  has  a 
conical  point  fitting  into  an  indentation  in  0,  the  thread  end  of  the 
screw  being  fitted  to  a  tapped  hole  in  the  head  of  D. 

D  1  is  caused  to  rotate  with  L  by  a  pawl  and  ratchet,  through  about 
180°  for  each  stroke.  During  the  return  stroke  of  L,  D  1  remains  station- 
ary. The  pawl  and  ratchet  are  more  clearly  shown  in  Fig.  Ill  at  P. 


FIG.  ill. 


In  this  figure  the  feed-screw  is  hid,  being  covered  by  the  sleeve  S  by 
which  the  drill  is  fed  by  the  grip  of  the  hand. 

In  some  ratchet-drills  the  drill  is  rotated  during  both  the  forward 
and  reverse  strokes  of  the  lever.  With  such  a  machine  the  drilling  can, 
of  course,  be  done  much  faster.  Automatic  feed  mechanism  is  pro- 
vided in  the  higher-priced  machines. 

The  Breast-drill.  —  This  machine  is  used  for  the  same  purpose  as 
the  ratchet-drill,  viz.,  for  drilling  odd  holes  in  work  which  cannot  con- 
veniently be  taken  to  the  power-drill.  Fig  112  shows  a  typical  breast- 
drill.  The  drill  is  held  in  a  chuck  at  E,  the  pressure  being  applied  by 
the  breast  at  B.  The  handle  H  rotates  the  drill  while  /  is  held  in  the 
left  hand  to  steady  the  machine.  This  machine  may  be  changed  from 
fast  to  slow  speed  by  turning  the  thumb-screw  at  A.  It  will  not  drill 
as  large  holes  as  the  ratchet-drill,  1/2/'  being  about  the  largest.  One 
could  not  drill  many  1/2//  holes  before  experiencing  soreness  of  the  breast. 

The  Fifield  Drilling  Attachment. — Figs.  113  and  114  show  a  very 
handy  drill  which  is  operated  in  connection  with  a  common  carpenter's 


76 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  113. 


FIG.  112. 


FIG.  114. 


DRILLING-MACHINES 


77 


brace,  the  drill  being  held  to  the  work  by  a  chain.  This  device  has 
automatic  feed  and  ball  bearings,  and  for  drilling  holes  up  to  3/V'  diam- 
eter it  is  much  in  demand  by  machinists  and  other  metal-workers. 

Portable  Drill. — The  portable  Urill,  Fig.  115,  is  designed  to  be  driven 
from  the  line-shaft  or  other  powe&mechanism,  and  yet  it  may  be  moved 


FIG.  115. 

about  independently  of  the  latter.  It  is  driven  by  a  belt  running  on 
the  tight  and  loose  pulleys  T  and  L,  and  is  designed  to  be  used  mainly 
in  the  erecting-room  of  the  machine-shop. 


78 


MACHINE-SHOP  TOOLS  AND  METHODS 


P4 


In  using  this  machine  the  hanger  H  is  fastened  near  the  main  shaft, 
and  the  drilling-machine  secured  to  the  work  by  bolts  passing  through 
the  base  B.  The  rope  R,  which  runs  over  the  pulley  P,  is  made  in 
sections  to  admit  of  the  machine  being  operated  at  various  distances 
from  the  hanger  H.  The  machine  has  universal  adjustments  by  means 
of  the  ball  joint  J,  handle  H  1,  and  sockets  S.  Having  adjusted  the 

machine  so  that  the  drill  D  is  in  po- 
sition for  the  first  hole,  a  number  of 
other  holes  may  be  drilled  without 
removing  the  base  B.  Tension  on 
the  rope  is  maintained  by  a  weight 
at  W,  and  the  drill  is  fed  by  hand- 
wheel  H  2. 

This  machine  has  automatic  feed 
also.  For  this  purpose  a  cone-pulley 
hid  behind  P  is  belted  to  the  upper 
cone  C.  The  latter  operates  a  worm 
and  worm-wheel,  which  in  turn  ac- 
tuate a  feed-nut  on  screw  F. 

Portable  power-machines  are 
made  in  various  designs,  some  of 
which  are  smaller  than  the  one 
above  described.  The  Stowe  flexi- 
ble shaft,  used  in  dental  work,  is  also 
employed  in  connection  with  portable 
drills. 

The  Sensitive  Drill. — This  ma- 
chine, a  good  example  of  which  is 
shown  in  Fig.  116,  is  a  stationary 
power-drill,  designed  for  very  small 
holes.  It  is  fed  by  hand,  and  it  is 
made  very  light  and  sensitive,  so  that 
any  undue  strain  on  a  small  drill  may  be  felt  through  the  lever  L  3  by 
which  the  drill  is  fed.  The  object  of  this  is  to  prevent  breaking  the 
drills. 

The  Spindle  S  is  counterbalanced  by  a  weight  suspended  in  the 
hollow  column  C.  The  head  H  carries  a  quill  or  sleeve  Q  in  which 
the  lower  end  of  the  drill-spindle  is  journaled,  the  upper  end  being 
journaled  in  the  frame.  The  sleeve,  and  with  it  the  spindle,  is  fed 
to  the  work  by  means  of  a  rack-and-pinion  movement.  The  pinion 


116. 


DRILLING-MACHINES  79 

(small  gear)  is  on  the  same  shaft  with  the  feed-lever,  the  rack  being 
secured  to  the  sleeve.  The  head  is  adjustable  vertically. 

The  Table  T  is  designed  to  be  tilted  to  an  angle,  and  to  swing  around 
the  column  to  bring  the  work  in  position  for  drilling  holes  in  different 
positions.  It  is  clamped  by  the  lever  L  2.  The  round  table  R  is 
adjustable  vertically,  and  may  oe  lifted  out  of  its  socket  and  either 
C  1  or  C  2  inserted.  The  first  of  these  is  designed  to  support  the  lower 
end  of  shafts,  etc.,  while  drilling  centers  for  lathe  work;  the  other  is 
used  as  a  rest  for  cylindrical  work  when  the  same  is  to  be  drilled  at 
right  angles  to  its  axis. 

The  machine  is  driven  by  the  counter-shaft  C  3.  It  requires  three 
belts.  The  first  runs  between  the  shop  line-shaft  and  the  tight  and 
loose  pulleys  T  and  L.  The  second  connects  the  cone  pulley  P  1  with 
a  similar  cone,  P  2.  The  third  belt  runs  over  the  pulleys  P  3,  P  4, 
P  5,  and  P  6,  and  thus  operates  the  spindle  S  which  carries  the  drill. 
When  the  machine  is  idle  the  main  belt  runs  on  the  loose  pulley  L. 
To  start  the  machine  the  belt  is  shifted  to  the  tight  pulley  T7  by  a  suit- 
able lever. 

These  machines  are  made  with  any  number  of  spindles  up  to  twenty. 

Sensitive  Friction-drill. — The  drill  illustrated  in  Fig.  116  has  three 
changes  of  speed  by  cone  pulleys.  Fig.  117  shows  a  machine  designed 
for  the  same  class  of  work,  but  it  has  no  cone  pulleys  of  the  ordinary 
type,  the  spindle  speed  being  changed  by  moving  the  friction  pulley  P 
nearer  to  or  farther  from  the  center  of  the  driving-cone  D.  The  fric- 
tion pulley  is  in  contact  with  both  of  the  cones  D  and  D  1,  and  D,  being 
driven  by  the  belt  B,  transmits  motion  to  D  1.  P  is  supported  by 
the  yoke  which  slides  and  swings  on  shaft  S,  and  is  moved  to  or 
from  the  center  of  D  by  the  knob  K.  The  driving-cone  D  may  be 
adjusted  vertically  to  increase  its  friction  on  P. 

Back-geared  Drill. — The  upright  drill  shown  in  Figs.  118  and  119  is 
designed  for  much  heavier  work  than  the  sensitive  drills.  The  frame 
is  a  great  deal  stronger  and  the  driving  mechanism  is  much  more  power- 
ful. The  spindle  S  is  driven  by  a  belt  connecting  the  cone  pulleys 
P,  P  1,  and  by  the  bevel-gears  G.  When  the  back  gears  G2  and  G  3 
(Fig.  119)  are  brought  into  mesh  with  G  1  and  G  4  the  spindle  speed 
is  reduced  to  such  an  extent  that  the  fastest  speed  "in  gear"  is  slower 
than  the  slowest  speed  "out  of  gear."  Thus  we  have  four  speeds  (due 
to  the  four  steps  on  the  cone  pulley)  "out  of  gear,"  and  four  different 
speeds  "in  gear,"  making  eight  speeds  in  all.  These  speeds  should 
be  in  geometrical  progression. 


80 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  operation  of  the  back  gear  is  as  follows :  The  gear  G  1  is  secured 
to  the  pulley  P,  and  gear  and  pulley  together  turn  freely  on  the  shaft 


FIG.  117. 


S  1,  and  may  turn  at  a  different  speed  from  the  latter.     C  is  a  clutch 
having  teeth  on  the  right-hand  end  designed  to  engage  with  mating 


FIG.  118 


81 


DRILLING-MACHINES  83 

teeth  on  the  gear  G  1  as  shown.  This  clutch  is  connected  to  the  shaft 
S  1  by  a  key  which  causes  the  clutch  to  turn  with  the  shaft,  but  leaves 
it  free  to  be  moved  endwise.  Gears  G  2  and  G  3  are  cast  integral,  being 
joined  together  by  a  sleeve  in  1^he  center  of  which  a  groove  is  turned 
to  receive  a  U-shaped  shifter  pivoted  in  the  lever  L.  This  lever  has  a 
similar  connection  with  the  clutch  C,  and  it  is  fulcrumed  on  the  frame 
below  the  gears.  If  the  lever  be  moved  toward  the  left,  it  will  cause 
clutch  C  to  engage  with  G  1  and  at  the  same  time  move  the  gears  G  2 
and  G  3  to  the  left,  disengaging  them  from  G  I  and  G  4.  If  the  lever 
be  moved  toward  the  right,  it  will  bring  both  the  clutch  and  gears  to 
the  position  shown  in  the  figure,  which  is  the  "in-gear"  position  for 
the  back  gears.  If  now  pulley  P  be  caused  to  revolve,  it  will  turn  at 

/"*  o  /nr   A 

a  ratio  with  shaft  S  1  depending  on  the  ratio  of  ^y  multiplied  by  -*-% , 

G4  being  tightly  keyed  to  S  1.  Assuming  that  G  1  has  20  teeth,  G  2 
40  teeth,  G  3  20  teeth,  and  G  4  40  teeth,  then  the  ratio  of  revolutions 

40 
of  the  cone  pulley  to  the  revolutions  of  shaft  S  1  will  equal  ^  multi- 

40 

plied  by  ^  equals  4.     When  clutch  C  is  in  engagement  with  G  1,  the 

back  gears  being  out  of  gear,  shaft  S  1  will  be  turned  directly  by  the 
cone  pulley,  and  the  ratio  will  be  1  to  1.  This  ratio  is  suitable  for 
drilling  small  holes,  and  the  ratio  due  to  the  engagement  of  the  back 
gears  is  suitable  for  the  larger  work.  The  gain  in  power  is  in  accord- 
ance with  the  well-established  law  that  (other  things  being  equal) 
power  is  proportional  to  speed.  However,  the  source  of  this  power 
is  not  in  the  machine,  but  in  the  boiler-furnace. 

Feed  Gearing. — On  the  spindle  S  is  a  pulley  P  2  having  belt  con- 
nection with  the  pulley  P  3.  On  the  lower  end  of  the  shaft  S  2  (Fig. 
118),  to  which  P  3  is  keyed,  are  three  spur-gears  numbered  1,  2,  and 
3.  Either  of  these  gears  may  be  caused  to  revolve  with  the  pulley 
P  3  by  a  sliding  key,  which  key  is  moved  by  the  knob  K.  Keyed  to 
the  feed-shaft  S  3  are  three  other  gears,  numbered  4,  5,  and  6,  meshing 
with  the  first  three.  When  the  sliding  key  is  in  the  gear  No.  1,  it 
causes  that  gear  to  revolve  with  the  shaft  S  2,  and  motion  is  thereby 
transmitted  to  gear  No.  4  on  shaft  S  3,  the  number  of  revolutions  of 
No.  4  depending  upon  the  ratio  of  the  diameter  of  No.  1  to  the  diameter 
of  No.  4.  At  the  same  time  the  other  two  gears  on  S  3  revolve,  carry- 
ing the  two  mating  gears  on  shaft  S  2  with  them,  but  as  the  sliding 
key  at  this  time  has  no  connection  with  these  two  gears  they  merely 


84  MACHINE-SHOP  TOOLS  AND  METHODS 

revolve  idly  on  the  shaft  S  2.  If  the  sliding  key  be  moved  so  as  to 
connect  gear  No.  2  to  the  shaft  S  2,  the  feed-shaft  will  be  caused  to 
revolve  at  a  speed  depending  on  the  ratio  of  the  diameter  of  gear  No.  2 
to  gear  No.  5  on  shaft  S  3.  The  other  two  gears  on  shaft  S  2  will  revolve 
idly,  and  so  on  with  the  third  pair  of  gears.  Thus  we  obtain  three 
different  speeds  of  the  shaft  S  3  and  feeds  of  the  spindle  S,  as  will  be 
shown  later. 

On  the  lower  end  of  the  shaft  S  3,  Fig.  120,  is  a  bevel  pinion  operating 
the  worm-shaft  and  worm  W  by  means  of  the  bevel-gear  G  6.  The 
worm  W  operates  the  worm-wheel  W  1,  and  on  the  shaft  same  with  W  1 
is  a  small  gear  meshing  into  the  rack  R,  which  is  bolted  to  the  quill  Q. 
The  quill  Q  does  not  turn  in  the  head  H,  but  is  fed  vertically  at  three 
different  rates  by  the  train  of  mechanism  just  outlined.  The  spindle  S 
revolves  in  the  quill  Q  and  is  forced  by  the  collars  C  1  and  C  2  to 
follow  the  vertical  movement  of  the  quill. 

The  bevel-gear  G  6  is  not  rigidly  connected  to  the  worm-shaft  W, 
but  is  caused  to  turn  with  the  latter  by  tightening  the  knurled  nut  N. 
This  nut  screws  on  a  small  shaft  passing  through  the  center  of  the  worm- 
shaft,  and  on  the  other  end  of  the  small  shaft  is  a  friction-clutch  de- 
signed to  engage  with  a  friction -clutch  on  the  bevel-gear  G  6. 

Automatic  Stop. — On  the  quill  Q  is  a  movable  collar  C  3  which  may 
be  tightened  in  any  position  on  the  quill.  If,  when  the  machine  is  in 
operation,  the  nut  N  be  tightened,  it  will  set  in  motion  the  bevel-gear  G  6, 
and  with  it  the  intervening  mechanism,  including  the  quill  Q.  As  the 
latter  feeds  downward  it  engages  with  the  trip  T,  disengaging  the  latch 
L  1  from  the  lever  L  2.  This  lever  is  so  connected  to  the  worm-bracket 
that  when  the  lever  is  disengaged,  it  permits  the  worm  W  to  drop  out 
of  mesh  with  the  worm-wheel  W  1 .  Thus  the  downward  feed  of  the  spindle 
S  may  be  automatically  stopped  at  any  required  depth,  the  quill  Q  being 
graduated  for  adjustment  of  the  collar  C  3. 

Hand-feed — Quick  Return. — The  above  description  of  Fig.  120  has 
reference  to  the  automatic  feed  of  the  drill-spindle  S.  By  slackening  the 
nut  N  the  spindle  may  be  fed  by  hand  by  the  hand-wheel  H.  After 
drilling  a  hole  the  spindle  may  be  quickly  returned  by  tripping  the  lever 
L  2  and  turning  the  lever  L  3. 

Vertical  Adjustment  of  Head. — The  head  H  I  may  be  adjusted  and 
clamped  in  any  position  on  the  vertical  face  F. 

Table  Adjustment. — Work  may  be  clamped  to  the  table  T  or  to  the 
base  B,  Fig.  118.  The  table  is  supported  on  the  arm  A  and  may  be 
revolved  around  the  column  C  4  and  adjusted  vertically  on  the  column. 


DRILLING-MACHINES 


85 


The  table  may  also  be  revolved  on  its  own  axis.     These  adjustments 
facilitate  drilling  holes  in  different  positions  and  in  different  heights  of 


FIG.  120. 

work.     Thus  having  clamped  a  piece  of  work  to  the  table  T,  holes  may 
be  drilled  in  any  position  within  the  circumference  of  the  table  without 


86  MACHINE-SHOP  TOOLS  AND  METHODS 

unclamping  the  work.  The  base  has  no  such  adjustments,  and  con- 
sequently work  held  on  the  base  must  be  readjusted  for  holes  in  different 
positions. 

RADIAL   DRILLS 

General  Description.  —  Fig.  121  shows  a  perspective  view  of  a 
radial  drill,  so  called  from  the  long  radial  arm  common  to  all  machines 
of  this  class;  and  Figs.  122-7  show  auxiliary  views  of  the  same  machine. 
Similar  reference-letters  refer  to  similar  parts  throughout  the  several 

G  11 


FIG.  121. 

views.  Referring  to  the  perspective  view,  the  base  B,  table  T,  column 
C,  arm  A,  and  head  H  comprise  the  principal  members  of  the  machine. 
The  column  C,  carrying  the  arm  A,  swings  around  the  stump  S  (Fig. 
123)  through  a  complete  circle  when  the  machine  is  driven  from  below, 
and  through  about  340°  when  driven  from  above.  In  the  latter  case 
the  movement  of  the  arm  is  limited  only  by  the  driving-belt.  The 
head  H  (Fig.  121)  slides  on  the  planed  ways  of  the  arm  A,  and  with 
the  arm  may  be  raised  and  lowered  on  the  column  for  different  heights 
of  work.  This  vertical  movement  of  the  arm  is  effected  by  a  shaft 
within  the  column,  in  connection  with  gears  G  11  on  top  of  the  column. 
These  gears  operate  a  screw  S  1  passing  through  a  threaded  nut  in 
the  arm  A,  as  shown  in  Fig.  124.  This  mechanism  for  raising  the  arm 
is  operated  by  a  lever  within  easy  reach  of  the  workman. 


DRILLING-MACHINES 


87 


Arrangement  of  the  Driving-shafts. — The  shafting  between  the 
driving-pulley  and  drill-spindle  in  a  radial  drill  necessarily  follows  a 
rather  circuitous  route.  Unless  >th"e  shafting  be  amply  large  there  will  be 
a  considerable  angle  of  torsion  between  these  two  points.  This  shafting 
is  mostly  hid  in  Fig.  121,  but  it  may  be  traced  by  the  aid  of  Figs. 
122, 123, 124,  and  125.  Thus,  starting  at  the  pulley-shaft  S  3  in  Fig.  122, 
connection  is  made  between  this  and  shaft  S  4  by  the  four  pairs  of  gears 


FIG.  122. 

shown.  These  gears  give  four  different  speeds  to  the  shaft  S  4.  The 
latter  drives  the  vertical  shaft  S  2  by  means  of  the  miter-gears  G  9  and 
G  10,  Fig.  123.  Now  referring  to  Fig.  124,  shaft  S  5  is  driven  by  S  2. 
Through  a  system  of  gearing  shown  in  the  gear-box  B  2,  the  shaft  S5 
transmits  motion  to  the  bevel-gear  G  12.  This  in  turn  drives  the  shaft 
S  6  by  means  of  the  bevel-gear  G  13,  shaft  S  7,  and  bevel-gears  G 14 
and  G  15.  Finally,  the  drill-spindle  S  8  receives  its  motion  through 
the  gear  Cr  16,  which  meshes  with  gear  17,  these  two  gears  being  on  the 
shaft  S  6  and  spindle  S  8  respectively. 

Reversing  Mechanism. — As  this  particular  machine  is  designed  to 
be  used  in  tapping  as  well  as  in  drilling  holes,  there  are  two  bevel-gears 
on  the  shaft  S  7,  one  of  these,  G  18,  being  hid  behind  the  spindle  counter- 
weight W  3  in  Fig.  124,  but  shown  in  Fig.  125.  Both  of  the  gears  G  14 


88 


MACHINE-SHOP  TOOLS  AND  METHODS 


and  G  18  mesh  with  G  15,  but  are  inoperative  unless  engaged  by  a 
clutch  between  the  two  gears.  This  clutch  is  secured  to  shaft  S  7  by 
a  key  *  which  causes  it  to  rotate  with  the  shaft  and  at  the  same  time 


11 


FIG.  123 

leaves  it  free  to  travel  lengthwise  of  the  shaft  by  the  movement  of  the 
head  H  along  the  arm  A.  The  object  of  this  arrangement  is  to  give 
both  a  forward  and  reverse  movement  to  the  drill-spindle,  the  forward 

*  The  instructor  is  advised  to  make  on  the  blackboard  a  sectional  view  of  G  14, 
showing  the  key. 


DRILLING-MACHINES  89 

movement  being  used  for  drilling  and  tapping  holes,  and  the  reverse 
movement  for  backing  the  tap  out. 

This  method  of  getting  a  forward  motion  by  engaging  the  clutch 
with  G  14  and  a  reverse  motton  by  engaging  it  with  G  18  should  be 
particularly  noted  by  the  student?  The  clutch  is  shifted  by  the  handle 
H  3,  Figs.  124  and  125. 

Feed-gear.— The  feed-shaft,  S  9,  Fig.  125,  is  driven  from  the  drill- 
spindle  by  spur-gears  as  shown.  At  the  lower  end  of  S  9,  and  in  the 


G  11 


FIG.  124 

gear-box  B  3,  Fig.  126,  is  a  system  of  gearing  by  which  eight  different 
speeds  are  communicated  to  the  worm  W,  the  handle  for  same  being 
within  easy  reach.  The  worm-wheel  W  1,  which  is  driven  by  W,  has 
on  the  inner  end  a  small  gear  G  19,  Fig.  125,  which  gives  motion  to 
G  20.  On  the  same  shaft  with  G  20  is  a  pinion  (small  gear),  giving 
vertical  movement  to  the  drill-spindle  S  8  by  meshing  with  the  rack  R, 
Fig.  126. 

The  Hand-feed  and  Quick  Return. — We  have  in  the  above  train  of 
gears  a  very  efficient  and  convenient  system  of  mechanism  for  the 
automatic  feed.  When  it  is  desired  to  feed  the  spindle  by  hand  the 
worm-shaft  W  is  disengaged  from  the  gearing  in  feed-box  B  3,  Fig. 
126,  and  the  spindle  is  fed  by  hand-wheel  H  1.  The  drill  is  quickly 


90 


MACHINE-SHOP  TOOLS  AND  METHODS 


withdrawn  from  the  drilled  hole  by  pushing  in  lever  L  and  turning  it 
at  the  same  time.  The  effect  of  pushing  this  lever  in  is  to  disengage 
the  clutch  which  binds  the  worm-wheel  W  1  to  its  shaft. 

No  automatic  movement  of  the  head  H  is  needed.  It  is  moved  by 
the  hand-wheel  H  2,  Fig.  126.  H  2  operates  the  worm  and  worm-wheel 
shown,  and  these  give  motion  to  a  pinion  meshing  into  the  rack  R  2. 


G16 


H  2 


FIG.  125 

The  Depth  Gage. — This  machine  is  provided  with  a  depth  gage  of 
unique  design,  shown  in  connection  with  G  20,  Fig.  126.  The  grad- 
uated dial  may  be  set  at  zero  independently  of  the  spindle,  and  several 
different  depths  of  holes  may  be  drilled  without  disturbing  the  dogs, 
which  are  set  by  the  dial  as  required.  Thus,  suppose  the  two  dogs 
D  and  D  1  to  be  set  for  drilling  holes  9"  and  12"  deep  alternately;  hav- 
ing drilled  a  9"  hole,  it  is  necessary  only  to  lift  the  latch  L  1  an  instant 


DRILLING-MACHINES 


91 


to  let  the  first  dog  clear  it  when  drilling  the  12"  hole.  It  will  be  under- 
stood that  when  one  of  the  dogs  strikes  the  latch  it  causes  the  feeding 
to  cease  by  the  disengagement. of  the  clutch  C  2.  The  latter  maybe 

disengaged  by  hand  by  the  Handle  shown,  and  to  avoid  damaging  the 

' 


H2 


FIG    126 


mechanism  it  is  automatically  disengaged  when  the  drill-spindle  has 
reached  the  extreme  end  of  its  travel. 

Detailed  Description  of  the  Gearing  in  the  Gear-boxes.— The  sixteen 
speeds  of  S  8,  given  by  the  combination  of  the  gears  in  gear-boxes  B  1 
and  B  2,  are  in  geometrical  progression  ranging  from  17  to  267  revolutions 


92 


MACHINE-SHOP  TOOLS  AND  METHODS 


per  minute.  So,  also,  are  the  eight  feeds  in  the  gear-box  B  3,  which  vary 
between  .007"  and  .064"  per  revolution  of  spindle.  All  of  these  speeds 
and  feeds  are  controlled  by  handles  within  easy  reach  of  the  operator. 
It  may  be  well  to  further  explain  these  gearing  systems. 

Referring  to  Fig.  122,  the  four  gears  G  1,  G  2,  G  3,  and  G  4  are  tightly 
keyed  to  shaft  S  3,  while  only  one  of  the  matmg-gears  can  be  locked 
at  one  time,  the  clutches  C  3  and  C  4  being  used  for  this  purpose.  The 
velocity  ratio  of  the  shafts  S  3  and  S  4  depends  on  the  ratio  of  the  diam- 
eters of  the  pair  of  gears  which  control  the  speed  at  any  given  time. 
When  one  of  the  gears  on  shaft  S  4  is  locked  the  other  three  revolve 


FIG.  127 

idly,  as  was  explained  in  connection  with  the  sliding-key  gears  shown  in 
Figs.  118  and  119. 

The  gearing  in  gear-box  B  2,  which  takes  the  place  of  "back  gears/' 
is  somewhat  more  complicated.  The  highest  speed  is  obtained  by 
speeding  up  at  this  particular  part  of  the  machine.  Inasmuch  as  the 
gears  for  elevating  the  arm  must  be  thrown  in  mesh  by  tumbler  action, 
it  is  necessary  that  these  gears  run  at  a  comparatively  slow  speed,  and 
this  is  the  principal  reason  for  speeding  up  the  back  gears. 

Fig.  127  shows  a  sectional  view  of  the  sliding-key  gears  in  gear-box 
B  3.  These  are  driven  by  four  other  gears  tightly  keyed  to  a  shaft  in 
the  box.  The  key  A  is  moved  lengthwise  in  the  hollow  shaft  by  the 
engagement  of  gear  G  21  with  the  rack  B,  the  gear  being  rotated  by  the 
lever  C.  The  key  may  be  held  in  a  position  for  locking  either  of  the  four 
gears,  and,  from  what  has  already  been  said  respecting  such  systems, 
it  will  be  readily  understood  that  the  velocity  ratio  at  any  given  time 
will  depend  upon  the  ratio  of  the  pair  of  gears  which  control  the  speed 


DRILLING-MACHINES  93 

at  that  time.  The  four  speeds  given  by  these  gears  are  changed  by 
other  gears  in  the  box,  so  as  to  give  eight  speeds  in  all. 

The  student  should  note  the  difference  between  the  main  driving- 
mechanism  in  this  machine  and  that  in  which  a  stepped  cone  is  used.  It 
may  be  remarked  in  this  connection  that  there  is  a  growing  tendency  in 
machine-tool  design  to  substitute  gearing  for  cone  pulleys.  The  manu- 
facturers of  this  machine  claim  that  they  were  the  first  to  use  gearing 
in  place  of  the  main  driving  cones. 

An  Important  Principle  in  Design. — It  is  generally  understood  by 
designers  that  box  and  tubular  forms  of  framework  are  well  adapted  to 
resist  the  stresses  to  which  machine-tools  are  subjected.  But,  as  a  rule, 
these  forms  have  not  been  adopted  in  designing  the  arms  of  radial  drills. 
However,  the  designer  of  the  machine  just  described  has  so  arranged 
the  mechanism  connected  with  the  head  as  to  admit  of  the  arm  being 
made  of  approximately  tubular  cross-section.  In  the  factory  where  this 
machine  was  built  3/8"  holes  have  been  drilled  with  a  feed  of  nearly  .06" 
per  revolution  of  drill  before  the  drill  failed,  the  regular  feed  for  such 
drills  being  about  .006".  The  manufacturers  of  the  drilling-machine 
referred  to  attribute  this  extraordinary  performance  to  the  torsional 
stiffness  of  the  arm.  Mr.  F.  G.  Halsey,  associate  editor  of  the  "American 
Machinist,"  in  an  editorial  in  that  journal  July  24,  1902,  illustrates  the 
theory  held  by  Mr.  Norris,  the  designer  and  patentee  of  the  machine,  as 
follows:  " Let  the  reader  take  a  piece  of  common  pasteboard  mailing- 
tube,  8  to  10  inches  long,  in  the  two  hands  and  twist  it.  It  will  of  course 
be  found  to  be  quite  stiff  and  unyielding.  Next  slit  the  tube  its  entire 
length  with  a  penknife,  as  shown  in  Fig.  128,  and  twist  it  again.  Its 


FIG.  128. 

stiffness  against  torsion  will  be  found  to  be  gone.  There  is  simply  no 
comparison  in  the  strength  of  the  tube  before  and  after  slitting.  In  the 
former  condition  it  has  a  good  deal  of  strength,  while  in  the  latter  it  has 
none.  When  the  tube  is  slit  and  then  twisted  the  two  edges  of  the  cut 
slide  on  one  another  in  the  manner  which  we  have  tried  to  show  in  the 
illustration,  and  this  sliding  takes  place  with  the  most  trifling  effort." 
Mr.  Halsey,  in  the  editorial  a  part  only  of  which  has  been  quoted, 


94 


MACHINE-SHOP  TOOLS  AND  METHODS 


does  not  quite  agree  with  Mr.  Norris.  He  says  in  effect  that  while  the 
ordinary  radial  drill-arm  has  a  deep  gap  on  one  side,  this  gap  is  closed 
at  each  end,  and  this  metal  on  the  ends  must  in  a  measure  resist  the 
sliding  tendency  of  the  edges  of  the  gap.  He  attributes  the  extraordi- 
nary results  hi  part  to  improvements  in  the  twist-drill. 

The  3/s"  holes  in  the  test  mentioned  above  were  drilled  in  cast  iron 
from  the  solid.  While  such  results  cannot  be  realized  in  average  prac- 
tice, it  may  be  reasonably  inferred  that  the  feeds  recommended  by  the 
manufacturers  of  twist-drills  may,  under  favorable  conditions,  be  consid- 
erably increased.  This  is  no  reflection  upon  the  drill-makers,  but  rather 


FIG.  129 


FIG.  130. 


it  is  an  indication  that  they  have  underestimated  the  value  of  their 
product. 

Motor-driven  Radial  Drills. — Fig.  129  shows  a  rear  view  of  the  drilling- 
machine  that  has  been  described,  in  connection  with  a  3-H.P.  constant- 
J  speed  motor;    and  Fig.  130   shows   the  machine  as  modified  to  adapt 
1  it  to  a  3-H.P.  variable-speed  motor.     In  the  former  case  the  machine  has 
16  speeds,  the  same  as  when  driven  by  one  belt.     When  the  variable- 
speed  motor  is  used  the  drill  speeds  are  controlled  partly  by  the  motor 
and  partly  by  the  gearing  in  the  gear-box  B  2.     In  this  case  gear-box 
B  1  is  not  used. 

It  may  be  of  interest  to  the  student  to  know  that  these  machines, 
which  require  a  3-H.P.  motor,  are  designed  to  drill  holes  from  1/2  to 
3l/2  inches  diameter. 

Universal  Radial  Drills. — The  plain  radial  drills  above  described  are 
so  designed  that  holes  cannot  be  drilled  at  any  angle  with  the  horizontal 


DRILLING-MACHINES  95 

other  than  a  right  angle.  Fig.  131  shows  a  universal  radial  drill. 
The  arm  in  this  machine  may  be  rotated  on  its  axis  and  clamped  in  any 
position,  and  the  head  may  be  rptated  in  a  plane  parallel  to  the  face  of 
the  arm.  With  these  adjustments  holes  may  be  drilled  at  any  angle. 
The  extreme  end  of  the  arm  of  ^his  machine  may  be  supported  against 
springing  by  a  tie  from  the  base. 

Drills  are  also  made  with  only  one  of  the  angular  movements.     Such 
machines  are  called  semi-universal  radial  drills. 


FIG.  131. 


Tilting-table. — In  Fig.  132  is  shown  a  table  designed  to  be  used  with 
the  plain  radial  drill  for  angular  drilling.  The  table  may  be  tilted 
through  90°  by  means  of  the  crank  and  worm-gearing.  It  also  swings 
on  its  axis. 

MISCELLANEOUS    DRILLING-MACHINES 

Suspension  Drills,  etc. — The  drilling-machines  already  shown  are 
approximately  typical  of  their  several  classes.  There  is,  however,  a 
great  variety  of  designs  of  these  machines.  We  have  post-drills,  wall- 
drills,  overhead  traveling  drills,  suspension  drills,  etc.  One  design  of 
the  last-named  drills  is  illustrated  in  Fig.  133.  This  machine  has  eight 
speeds  and  three  automatic  feeds.  It  also  has  the  usual  hand-feed.  It 
will  be  seen  that  a  4-step  cone  and  back  gear  gives  the  eight  speeds, 


96  MACHINE-SHOP  TOOLS  AND  METHODS 

the  three  feeds  being  effected  by  the  two  3-step  cones  shown  on  the 
left. 

Such  machines  are  specially  adapted  to  large  plate  work  and  other 
work  requiring  wide  horizontal  area. 

Upright  Drill  with  Revolving  Table.— The  machine  illustrated  in 
Fig.  134  is  similar  to  the  common  upright  drill,  excepting  that  it  has  a 


FIG.  132. 

revolving  table  in  addition  to  the  revolving  spindle.  The  mechanism 
for  driving  the  table  is  separate  from  the  spindle-driving  mechanism, 
so  that  the  spindle  may  be  run  for  ordinary  work  without  running  the 
table.  The  object  in  this  design  is  to  better  adapt  the  drill  to  chuck 
work,  such  as  pulley  boring,  etc.  With  a  revolving  table  such  work 
can  be  more  quickly  " trued  up"  than  with  a  stationary  table.  The 
work  is  usually  cored,  and  a  boring-bar,  guided  by  a  bushing  in  the 
central  hole  of  the  table,  is  often  used  to  enlarge  the  hole.  Sometimes 
a  chucking-reamer  is  used  instead  of  the  boring-bar.  In  either  case  the 
hole  would  generally  be  finished  with  a  finishing-reamer. 

Multispindle    Drills.  —  Multispindle    and    gang  *  drills    are    manu- 
factured in  many  designs  and  for  many  different  kinds  of  work.     They 

*  These  terms  may  be  used  interchangeably. 


FIG.  133. 


97 


FIG.  134 


DRILLING-MACHINES  99 

are  made  to  drill  holes  in  straight  lines,  in  rectangles,  and  in  circles. 
They  may  be  made  also  for  holes  in  almost  any  curve.  In  some 
machines  the  distances  apart  of  the  drill-spindles  are  fixed;  in  others 
these  distances  may  be  changed.  *  The  spindles  may  be  driven  altogether 
by  belts,  in  which  case  one  belt  mfty  envelop  a  number  of  pulleys  (one 
on  each  spindle),  or  they  may  be  driven  partly  by  belts  and  partly 
by  gearing.  In  the  latter  case  there  may  be  one  central  gear  driving, 
by  intermediate  gears,  the  several  spindles,  or,  if  the  spindles  be  in  one 
straight  line,  they  may  be  driven  by  a  horizontal  shaft  and  bevel-gears. 
Fig.  135,  which  shows  a  machine  designed  especially  for  drilling  arch  bars, 
has  six  spindles,  and  these  are  so  bolted  to  the  frame  as  to  admit  of  limited 
adjustment.  The  horizontal  shaft  S  is  driven  by  the  cone  pulley  P 
and  spur-gears,  as  shown.  On  the  right-hand  end  of  this  shaft  is  an 
angular  shaft,  S  1,  driven  by  the  two  bevel-gears  G  and  G  1.  This 
shaft,  by  means  of  the  worm-  and  spur-gearing  shown  at  its  lower  end, 
automatically  feeds  the  table  and  work  to  the  revolving  drills. 

In  Fig.  136  we  have  a  multiple-spindle  drill  operated  by  a  belt  nearly 
the  same  as  in  the  sensitive  drill  of  Fig.  116.  The  upper  sections  of  the 
drill-spindles  in  this  machine  are  fixed  with  respect  to  the  driving-gear, 
but  the  lower  sections  are  adjustable  laterally  within  certain  limits, 
the  lower  bearings  being  separately  secured  to  the  framework  by  bolts 
held  in  T  slots.  The  connection  between  the  lower  section  of  each 
spindle  and  the  upper  section  is  made  by  means  of  the  well-known 
universal  joint.  If  the  student  is  not  familiar  with  this  kind  of  shaft 
connection,  he  may  find  it  on  almost  any  milling-machine. 

Turret-drills. — The  machine  shown  in  Fig.  137  is  radically  different 
from  any  previously  described  in  this  chapter.  The  main  driving 
mechanism,  consisting  of  tight  and  loose  pulleys  and  4-step  cones,  is  of 
ordinary  design;  but  the  connection  between  the  upper  driving 
mechanism  and  the  drill-spindles  is  novel.  Fig.  138  shows  an  enlarged 
view  of  the  upper  part  of  the  machine  with  the  pulleys  removed.  This 
machine  has  twelve  drill-spindles,  only  one  of  which  revolves  at  one 
time.  One  of  these  spindles  is  shown  at  S  in  the  figure.  A  description 
covering  the  operation  of  this  spindle  will  apply  equally  well  to  each 
of  the  twelve. 

On  the  right-hand  end  of  the  shaft  S  1  is  a  bevel-gear  G  meshing 
with  another  bevel-gear,  G  1,  which  is  loosely  keyed  to  the  driving-shaft 
S  2.  On  the  lower  end  of  S  2  is  a  clutch  that  engages  with  a  similar 
clutch  on  the  spindle  S  when  the  latter  is  in  operation.  Pivoted  at 
P  is  a  bell-crank  lever,  one  end  of  which  is  so  connected  to  the  spindle 


FIG    135. 


100 


FIG.  136. 


102 


MACHINE-SHOP  TOOLS  AND  METHODS 


S  2  as  to  give  vertical  movement  to  the  latter  when  the  lever  is  moved. 
The  other  end  of  this  lever  is  connected  to  a  lock-bolt  L  that  holds  the 
turret-head  in  position  when  one  of  the  drill-spindles  is  in  operation. 
The  other  levers  and  rod  connections,  L1,R1,  and  R  2,  lead  to  a  treadle 
movement  within  convenient  reach  of  the  workman.  When  the  treadle 

is  pressed  downward  it  draws  the 
lock-bolt  out  of  the  socket  S  3.  At 
the  same  time  the  shaft  S  2  is 
lifted  so  as  to  be  disengaged  from 
the  spindle  S,  in  which  position  it  is 
shown  in  the  engraving. 

As  was  stated,  only  one  drill 
or  other  tool  can  be  used  at  any 
given  time,  and  when  the  turret 
is  rotated  to  bring  a  second  tool 
into  operation,  the  lock-bolt  L 
will  automatically  enter  its  socket 
and  the  shaft  S  2  move  downward 
to  engage  and  drive  the  spindle 
S.  The  turret  is  revolved  by  hand 
to  bring  each  of  the  spindles  in 
adjustment  with  the  work,  as 
wanted. 

The  student  will  note  that  while 
this  machine  differs  from  the 
multiple-spindle  drills  in  that  only 
one  spindle  can  be  used  at  one  time, 
this  drill  has  a  very  decided  advan- 
•  tage  as  compared  with  a  one-spindle 

machine.  Thus  in  some  lines  of  work  it  is  necessary  to  perform  several 
operations  on  each  hole.  The  hole  may  need  to  be  drilled,  reamed, 
counterbored,  tapped,  etc.  In  this  machine  the  required  tools  having 
been  adjusted  once,  each  tool  may  be  quickly  brought  into  operation 
by  revolving  the  turret.  When  a  one-spindle  machine  is  used,  if 
each  hole  is  completed  with  one  adjustment  of  the  work  a  great  many 
adjustments  of  various  tools  will  be  required,  consuming  much  more 
time  than  merely  revolving  the  turret. 

Turret-drills  designed  especially  for  sewing-machine  details  will 
accomplish  an  almost  incredible  amount  of  work  in  a  day.  The  author 
has  on  his  desk  the  illustration  of  a  machine  made  by  the  National 


FIG.  137. 


DRILLING-MACHINES 


103 


Automatic  Tool  Company  which  is  represented  to  drill  19,000  holes 
every  ten  hours.  We  have  space  only  for  a  general  statement  of  the 
possibilities  in  this  class  of  machinery.  The  manufacturers  make  also 
a  somewhat  different  machine  which  "drills,  reams,  faces,  and  counter- 
bores  all  the  holes  in  a  sewing-machine  arm,  including  the  shaft-holes, 
without  taking  the  work  from  the  jig." 

High-speed  Attachment. — The  large  drilling-machines  run  entirely 
too  slow  for  holes  less  than  l/±"  diameter.  When  one  has  a  common 
upright  drill  or  any  large  drilling-machine,  but  no  sensitive  drill,  the 


FIG.  138. 

high-speed  attachment  shown  in  Fig.  139  is  very  handy.  It  will  be 
seen  that  the  shank  of  this  device  is  an  exact  counterpart  of  a  drill- 
shank,  and  it  may  be  used  in  the  spindle  of  the  drilling-machine  in  the 
same  manner  that  a  drill  is  used.  Within  the  casing  of  this  device 
is  a  system  of  gears  quite  similar  to  the  back  gears  on  the  upright  drill. 
There  is  this  difference,  however,  that  in  this  device  gears  increase 
the  speed  of  the  drill,  while  the  back  gears  decrease  the  speed  of  the 
drill-spindle.  The  drill  is  driven  by  the  small  chuck  shown,  and  the 
casing  is  held  stationary  either  by  hand  or  by  a  stop-pin  inserted  hi 
drilling-machine  table. 


104 


MACHINE-SHOP  TOOLS  AND  METHODS 


DRILLING-MACHINE    WORK    AND    METHODS    OF    CLAMPING     THE    WORK    TO 

THE   TABLE 

Character  of  the  Work.— The  principal  work  of  the  drilling-machine 
is,  of  course,  drilling  and  boring.*     It  is  also  used  for  machining  the 


FIG.  139. 

bosses  on  framework,  etc.,  and  sometimes  for  turning  the  periphery 
of  bosses  and  hubs.  When  made  for  both  forward  and  reverse  motions, 
as  many  drills  are,  the  drilling-machine  may  be  used  for  tapping  holes 
also. 

Starting  the  Hole. — To  drill  a  hole  we  first  indent  the  metal  with 
the  center-punch,  and  then  draw  a  circle  with  compasses  concentric 
to  the  center.  This  indentation  is  designed  to  direct  the  point  of 
the  drill,  but  from  various  causes  the  drill  does  not  always  follow  con- 
centrically with  the  circle.  It  is  necessary,  therefore,  in  starting  a 

*  The  term  boring,  as  used  in  the  machine-shop,  means  enlarging  a  hole. 


DRILLING-MACHINES  105 

hole  to  lift  the  drill  before  it  has  drilled  any  considerable  depth,  and 
ascertain  if  the  hole  is  following,  as  intended.  //  the  hole  has  started 
eccentrically,  a  small  groove  musfle  cut  on  the  long  side  of  the  eccentric 
m  order  to  cause  the  drill  to  incline  in  the  direction  of  the  groove  It 
is  sometimes  necessary  to  repeat  this  process  two  or  three  times  before 
the  drill  ,s  properly  started.  It  should  be  observed,  however  that 
the  work  of  correcting  the  drill  should  be  completed  before  the  hole  is  the 
full  dimeter.  A  diamond-point  chisel  or  cape-chisel,  or  even  a  center- 
punch,  will  answer  for  correcting  eccentricity  in  starting  a  hole  The 
groove  should  be  cut  clear  to  the  center 

Holding  Work  by  Bolts  and  Straps.-As  drilling-machine  tables 
are  always  made  with  slots  for  bolts,  one  of  the  first  methods  of  securing 
work  that  suggests  itself  is  by  means  of  bolts  and  straps  Fig  140 
shows  a  piece  of  work  thus  JH 

clamped.  The  straps  S  may  be 
made  of  flat  bars  of  machine- 
steel  from  i/2  to  3/4  inch  thick 
and  from  l»/4  to  23/4  inches 
wide,  according  to  the  character 
of  the  work.  Some  workmen 
prefer  to  make  the  straps  U-- 
shaped. A  piece  of  steel  8/s  to  FlG-  J40. 
Vs  inch  thick  and  about  1  inch  wide  makes  a  good  strap  Fie  141 

SHOWS    frm    <iria™-o    ^f    U^^-U     1  _:_  .  j  e  &' 


shows  top  views  of  both  kinds  of  straps. 


O        O 


o 


FIG.  141. 

The  bolts  may  be  V2  to  »/4  inch  diameter,  the  holes  or  opening 
m  the  straps  being  about  i/16"  larger.  Most  bolts  for  the  above  pur- 
pose  are  •/«"  diameter,  and  for  all  but  exceptionally  heavy  work  «/«" 
diameter  for  the  bolts  and  about  the  average  of  the  above  sizes  for 
straps  should  be  adopted  as  the  standard.  Fig.  142  shows  a  planer- 
infa^l,  m?yfbeulnserted  ^^  al™S  the  T  slot  (without  start- 

^      ^  ^  ^  tUmed  ab°Ut  90°  to  ^  «*  bolt- 
.      When  the  drill  has  the  same  kind  of  slots  these  bolts 

^  driI1-taWe  alSO"     K  the  Sl°ts  are  mer^  Angular 
ough  the  table,  a  bolt  made  square  or  rectangular  under 


head  a 
head 

Td 
and  pass 


106 


MACHINE-SHOP  TOOLS  AND  METHODS 


D7 


the  head  would  be  better.     The  machine  shown  in  Fig.  118  has  both 

kinds  of  slots. 

In  Fig.  143  is  shown  a  piece  of  work  secured  to  a  drill- table  by  a 
strap  and  a  screw-clamp.  The  clamp  is  used  merely 
to  show  another  and  very  convenient  method  of  hold- 
ing the  work.  For  blocking  under  the  ends  of  the 
straps  simple  blocks  of  wood  with  grain  in  direction 
of  pressure,  or  stepped  cast-iron  blocks  as  in  Fig. 
144,  or  small  jack-screws,  may  be  used. 

A  Wrong  Method. — In  Fig.  145  we  show  a  strap 
with  the  block  end  much  higher  than  the  work. 
This  is  incorrect  for  two  reasons:  first,  it  puts  more 
pressure  on  the  block  than  on  the  work;  second,  it 
damages  the  head  and  thread  of  the  bolt. 

Protecting  Finished  Work. — When  the  straps  or 
clamps  would  come  in  contact  with  the  finished  work 
surfaces  the  work  should  be  protected  by  a  strip  of 
sheet  brass  or  copper.  Pasteboard  or  lead  would  be 

better  for  highly  polished  work. 

Use  of   Angle-plates.  —  In  clamping  work  having   a  base  parallel 

to  the  required  holes,  a  device  called  angle-plate  or  knee-plate  may 

be  used.     A  piece  of  work  of  this  character  is  shown  in  Fig.  146.     The 


FIG.  142 


FIG.  143. 


FIG.  144. 


angle-plate  is  held  by  bolts  and  straps  or  by  clamps  to  the  table,  and 
the  work  is  secured  to  the  angle-plate. 

Holding  Work  in  the  Drill-vise. — In  Fig.  147  we  show  a  drill-vise 
which  is  used  in  connection  with  the  drilling-machine.  The  vise  is 
held  on  the  table  by  straps  or  clamps,  and  the  work  held  in  the  vise. 

Fig.  148  shows  a  vise  in  which  the  work,  having  been  once  clamped, 
may  be  drilled  at  different  angles ;  this  is  called  a  universal  vise. 


DRILLING-MACHINES 


107 


Holding  Round  Work.— A  shaft  or  similar  detail  may  be  held  in 
a  vise.,  but  in  some  cases  V  blocks  are  used  for  this  purpose.  Fig.  149 
shows  an  end  view  of  a  shaft 
ing  in  a  V  block.  Two  or 
blocks  may  be  required,~the  shaft 
being  held  down  by  straps.  In 
case  three  blocks  are  used,  two 
may  be  placed  directly  under  the 
straps,  and  the  third  block  so 
placed  as  to  support  the  shaft 
under  the  pressure  of  the  drill. 

The  dotted  lines  in  Fig.  149  show  a  method  of  setting  the  shaft 
central  by  a  try-square.     Having  established  the  center  by  a  center- 


FIG.  146. 


punch,  the  shaft  is  rotated  in  the  V  blocks  until  the  center  is  equidistant 
from  the  two  positions  of  the  square-blade.     A  hermaphrodite  caliper 


FIG.  147. 


set  to  the  radius  of  the  shaft  is  a  convenient  tool  to  use  in  adjusting- 
the  shaft.     However,  a  common  steel  rule  will  answer.     Various  methods 


108 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  clamping  work  are  shown  in  the  chapter  on  milling-machines  and 
elsewhere  in  this  work. 

Drilling  Oil-holes  in  Pulley-hubs. — Oil-holes  in  pulleys,  gears,  etc., 
are  often  drilled  at  some  inconvenient  angle.  The  attempts  to  drill 
work  of  this  character  without  substantial  apparatus  for  clamping  has 
probably  caused  more  disasters  than  any  other  work  done  at  the  drill. 


FIG.  148. 


FIG.  149 


Many  a  time  the  author  has  seen  a  pulley  break  loose  from  its  moorings 
and  swing  around  at  a  high  rate,  while  oil-cans,  monkey-wrenches, 
etc.,  were  flying  in  every  direction.  But  the  boy — "Oh,  where  was  he?" 
Nothing  better  for  holding  such  work  could  be  devised  than  the  tilting- 
chuck  shown  in  Fig.  150.*  The  plate  P  in  this  has  a  V  lug  to  receive 
the  pulley-rim,  and  the  lower  edge  of  the  plate  is  hinged  to  lugs  secured 
to  the  edge  of  the  drill-table.  The  brace  B  passes  through  a  slot  in 
the  table,  and  is  supported  by  a  rod  passing  through  one  of  a  number 
of  holes  drilled  through  the  brace.  The  angle  may  be  changed  by  placing 
the  rod  in  a  different  hole. 

Turning  Hubs,  etc. — In  Fig.  151  is  shown  a  cutter-head  for  turning 
hubs  and  bosses  on  large  framework  and  in  some  other  cases.  The  head 
is  secured  to  the  drill-spindle  by  the  key  M.  Another  key,  K,  passes 
through  the  arbor  F.  The  latter  serves  to  steady  the  device,  but  when 

*Cut  taken  from  article  by  Cornell  Ridderhof  in  "American  Machinist,"  vol. 
27,  page  127. 


DRILLING-MACHIN 


109 


the  hub  is  solid  the  arbor  cannot  be  used.  The  cutters  DD  are  held 
by  set-screws  as  shown.  (This  illustration  was  first  used  in  connection 
with  an  article  by  T.  B.  Burnita  in  "American  Machinist/'  vol.  27,  p.  90. 

The  author  has  made  and  used  a  cutter-head  similar  to  the  above 

&  ' 


FIG.  150. 

except  that  it  was  a  plain  cylindrical  shell  screwed  on  the  drill-spindle, 
with  cutters  in  the  lower  end  held  by  set-screws.  In  addition  to  the 
set-screws,  each  cutter  was  radially  adjustable  by  a  screw  having  a 
collar  at  its  outer  end  to  engage  with  a  recess  made  in  the  edge  of  the 
cutter.  This  was  a  very  satisfactory  device,  and  it  is  but  little  trouble 
to  cut  thread  on  the  drill-spindle  for  this  and  other  heads  or  chucks. 


110 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  tool  shown  in  Fig.  152  may  be  used  to  face  bosses,  and  by  making 
the  cutter  with  a  downward  projection  it  could  be  used  to  turn  the 
periphery  of  shallow  bosses  and  hubs. 

Adjusting  Work  in  Drilling-machine. — Some  workmen  who  are  care- 
ful to  chuck  work  very  accurately  in  the  lathe  seem  to  understand  no 


FIG.  151 

better  way  for  drilling-machine  work  than  to  set  the  work  by  the  eye 
and  the  point  of  the  drill.  This  method  is  "good  enough"  for  common 
bolt-holes  and  other  work  of  this  character,  but  for  reamed  shaft-bear- 
ings, holes  for  studs  for  cut  gears,  etc.,  it  is  better  to  use  the  method 
described  below.  In  marking  out  work  to  be  drilled  it  is  well  to  have, 
in  addition  to  a  circle  of  the  diameter  of  the  hole,  another  circle  some- 
what larger  than  the  hole.  The  larger  circle  would  be  used  to  test  the 
work  after  the  hole  had  been  drilled.  For  the  larger  sizes  of  holes  it 
is  desirable  also  to  have  a  third  circle  smaller  than  the  drill  to  test 


DRILLING-MACHINES 


111 


the  work  before  drilling  to  full  diameter.  We  might  say,  by  way 
of  parenthesis,  that  in  drilling  large  holes,  on  account  of  the  pressure 
required  to  make  the  large  drill  cut,  it  will  be  advantageous  to  precede 
the  large  drill  by  a  smaller  drill.  Having  marked  off  the  work  from 
a  fine  center,  it  may  be  very  accusately  adjusted  under  the  drill-spindle 
by  the  use  of  a  tram.  (In  the  case  of  a  cored  hole  the  hole  may  be  filled 
with  a  wooden  block  and  the  circle  marked  off  from  a  lead  or  zinc  tag 
fastened  near  the  center  of  the  block.)  To  make  the  tram,  take  a  hard- 


FIG.  152. 


FIG.  153. 


wood  stick  about  9"  long  and  shape  one  end  like  a  drill-shank  to  fit 
the  drill-spindle.  Closely  fit  a  wooden  pin  in  a  3/s"  hole  in  the  other  end, 
as  in  Fig.  153.  The  pointer  in  the  end  of  the  wooden  pin  may  be  made 
of  a  Vie"  drill-rod  or  of  common  wire.  The  tram  is  now  placed  in  the 
drill-spindle,  and  while  revolving  it  slowly  the  work  is  adjusted  until 
the  tram-point  follows  the  larger  circle,  the  pin  being  adjusted  radially 
to  suit  the  diameter  of  the  circle.  For  adjusting  the  face  of  the  work 
square  with  the  drill-spindle,  or  for  testing  the  top  surface  of  the  drill- 
table,  a  much  larger  tram  may  be  made  on  the  same  principle.  If 
the  revolving  tram  touch  the  surface  being  tested  at  three  or  four  points, 
it  proves  that  the  surface  is  at  right  angles  to  the  drill-spindle.  Work 
which  requires  the  degree  of  accuracy  indicated,  whether  cored  or 
drilled  from  the  solid,  should  generally  have  the  hole  trued  up  by  one 
or  more  cuts  with  cutters  in  a  boring-bar,  the  bar  being  guided  at  its 
lower  end  in  a  bushing  fitted  to  the  drill-table.  The  finishing  cut  may 
be  made  with  a  reamer. 


CHAPTER  VIII 
DRILLS  AND  DRILLING 

Definition  and  Classification. — A  drill  (in  the  primary  acceptation 
of  the  term)  is  a  tool  for  originating  and  enlarging  holes  in  metal.  We 
use  the  term  "originate"  to  distinguish  the  drill  from  the  reamer  and 
boring-bar,  which  can  be  used  only  in  enlarging  holes. 

Drills  may  be  classified  as  follows :  twist-drills,  Farmer  drills,  flat  drills, 
pin-drills,  tit-drills,  bottoming-drills  and  slotting-drills. 

The  Twist-drill.  —  Fig.  154  shows  the  typical  form  of  taper-shank 
twist-drill.  This  drill  derives  its  name  from  the  fact  that  it  was  originally 


FIG.  154. 

twisted  to  its  helical  shape  in  the  forge-shop.  The  present  method  is  to 
cut  the  flutes  or  grooves  in  a  milling-machine.  The  helical  form  of  the 
flutes  affords  free  cutting  lips ;  at  the  same  time  they  tend  to  lift  the  chips 
from  the  hole.  To  avoid  weakening  the  drill  too  much  the  flutes  are 
made  of  gradually  decreasing  depth  from  the  point  of  the  drill  to  the 
shank.  This  would  lessen  the  chip  room  were  it  not  for  the  fact  that  the 
pitch  of  the  spiral  is  increased  sufficiently  to  compensate  for  the  decrease 
in  depth  of  the  flutes.  Some  manufacturers,  however,  preserve  the 
uniform  cross-sectional  area  of  the  flutes  by  making  them  of  gradually 
increasing  width,  while  the  spiral  is  kept  constant  as  to  pitch. 

Twist-drill  Nomenclature. — Drills  in  general  consist  of  two  parts. 
The  end  by  which  the  drill  is  driven  is  called  the  shank,  and  that  part 
of  the  drill  between  the  shank  and  the  cutting  end  is  the  body  of  the 
drill,  or  the  drill  proper.  The  nomenclature  of  the  twist-drill,  however, 
is  more  complicated.  Referring  again  to  Fig.  154,  W  is  the  web,  LL  the 

112 


DRILLS  AND  DRILLING 


113 


lands,  GG  the  lips,  S  the  shank,  and  T  the  tang.     Similar  letters  refer  to 
similar  parts  in  Figs.  155"  and  156. 

Clearance  of  the  Twist-drill. — The  twist-drill,  as  well  as  other  drills, 
is  made  largest  in  diameter  at  the  cutting  end,  and  tapers  slightly  toward 
the  shank.  The  amount  of  this  t§per  varies  in  different  drills  according 
to  their  size  or  use  from' .00025"  to  .0015"  per  inch  of  length.  It  will 
thus  be  seen  that  a  twist-drill  is  slightly  smaller  in  diameter  when  worn 
short  than  when  new.  This  taper  is  to  give  the  drill  longitudinal  clear- 
ance and  prevent  its  binding  as  it  advances  through  the  hole. 


FIG.   155. 


FIG.  156. 


The  drill  is  also  given  clearance  in  another  way;  this  is  illustrated 
in  Fig.  155  by  the  space  C  between  the  outer  circle  and  the  body  of  the 
drill.  This  clearance  is  called  body  clearance.  It  begins  at  B  and  increases 
toward  the  back  edge  of  the  drill,  the  distance  AB  being  concentric. 
Lacking  body  clearance  a  drill  would  bind  and  heat,  and  it  would  take 
more  power  to  drive  it. 

And  finally  a  drill  must  have  lipjdeaxance,  or  heel  clearance  as  it  is 
sometimes  called.  Referring  to  Figs.  155  and  156,  lip  clearance  is  made 
by  grinding  the  heel  H  lower  than  the  lip  or  cutting  edge.  This  gives 
prominence  to  the  cutting  edges  and  enables  them  to  bite  or  take  hold 
of  the  metal.  The  Cleveland  Twist  Drill  Company  recommend  an 
angle  of  lip  clearance  of  12°  for  the  average  rate  of  feed,  and  15°  for 


114 


MACHINE-SHOP  TOOLS  AND  METHODS 


heavier  feeds.  The  line  E,  joining  the  two  cutting  edges  should  be, 
according  to  their  practice,  135°  with  the  cutting  edges.  When  this 
angle  is  much  less  than  135°  "  there  is  danger  of  the  drill  splitting  up  the 
web. "  Some  twist-drills  are  made  with  a  fine  mark  running  lengthwise  of 
each  of  the  flutes.  When  thus  made  the  line  E  should  join  these  marks. 
Grinding  the  Drill. — It  is  essential  in  correct  grinding  that  the  cutting 
edges  be  of  equal  length  and  form  equal  angles  with  the  axis  of  the  drill. 
The  proper  angle  is  59°,  the  included  angle  being  118°.  It  requires  con- 
siderable skill  to  grind  a  drill  correctly,  and  indeed  it  is  a  matter  of 
controversy  as  to  what  is  the  correct  form  of  that  part  of  the  drill  which 
comes  in  contact  with  the  emery-wheel.  Some  mechanics  think  this 
surface  should  be  that  of  a  segment  of  a  cylinder,  as  shown  by  dotted 
lines  in  Fig.  157.  Others  contend  that  the  surface  should  correspond  to 


b 


FIG.  157. 


a  segment  of  a  cone,  as  indicated  by  the  dotted  lines  of  Fig.  158.  The 
consensus  of  "opinion  favors  the  latter  method,  because  it  increases  the 
clearance  at  the  center,  where  most  clearance  is  needed,  and  because  less 
power  is  required  to  drive  the  drill  when  thus  formed. 

In  a  shop  where  many  twist-drills  are  used  it  will  pay  to  use  a  machine 
for  grinding  them.  There  are  several  good  designs  of  machines  for  this 
purpose  (see  chapter  on  Grinding-machines),  but  if  necessary  to  grind 
the  drills  by  hand,  the  following  instructions  taken  from  the  catalog  of 
the  Morse  Twist-drill  and  Machine  Company  will  be  of  value: 

"Prof.  Sweet  suggests  that  the  rear  of  the  lip  of  a  drill  be  removed, 
as  shown  by  Fig.  159;  this  makes  the  cutting  edge  much  like  a  flat  drill. 
Drills  properly  made  have  their  cutting  edges  straight  when  gound  to  a 


DRILLS  AND  DRILLING 


115 


Grinding  to  less  angle  leaves  the  lip  hooking, 
and  is  likely  to  produce  a  crooked  and  irregular  hole.  The  grinding 
lines  of  a  drill  are  placed  slightly  above  the  center,  to  allow  for  the 


FIG.  158. 

proper  angle  of  point,  which  is  an  important  factor.  This  angle  is 

an  index  to  the  clearance.     If  the  angle  is  too  much,  the  drill  cuts 

rank;    if   not   enough,  the   drill   may   not   cut.      Fig.  160   shows    a 


FIG.  159. 


FIG.  160. 


proper  angle.  In  Fig.  161  the  angle  is  too  sharp.  In  Fig.  162  the 
angle  runs  backward,  and  shows  the  want  of  clearance.  An  effective 
method  of  determining  the  clearance  is  to  set  the  point  of  the  drill  on 


FIG.  161. 


FIG.  162. 


a  plane  surface,  holding  a  scale  as  shown  in  Fig.  163;  by  revolving 
the  drill  its  clearance  is  shown,  as  well  as  the  height  of  the  cutting  lips, 
which  should  be  equal;  also  the  cutting  edges  should  be  of  exactly  equal 
length — any  inequality  of  lengths  doubles  itself  in  work.  To  strengthen 


116 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  drill,  the  center  is  made  thicker  toward  the  shank.  As  the  drill  is 
shortened  through  use  the  center  shows  thicker,  and  will  work  hard 
in  drilling.  To  overcome  this  the  center  should  be  thinned,  care  being 
taken  to  remove  an  equal  amount  of  stock  on  each  side,  and  so  keep 
the  point  central." 

In  connection  with  the  above  it  may  be  suggested  that  a  graduated 
try-square  is  often  used  instead  of  the  scale,  and  it  is  more  convenient 


163. 


than  the  latter.  A  sheet-metal  gage  could  be  cheaply  made  and  used, 
instead  of  the  protractor.  This  gage  should  have  a  bearing  along  the 
body  of  the  drill  of  about  5",  and  should  be  applied  in  the  same  man- 
ner as  the  protractor.  Its  angle  should  be  121°.  The  method  of 
applying  a  protractor  is  shown  in  Fig.  164. 


FIG.  164. 

Effect  of  Errors  in  Grinding  a  Drill. — A  drill  having  a  conical  point, 
or  some  equivalent  thereof,  is  guided  by  the  point  in  "drilling  a  hole 
from  the  solid."  If  the  point  be  "out  of  center,"  that  is  out  of  the 
axial  line  of  the  drill,  the  drill  will  make  a  hole  larger  than  its  own 
diameter.  A  somewhat  similar  effect  will  be  produced  if  the  two  cut- 
ting edges  are  not  of  the  same  angle.  It  must  not,  however,  be  inferred 
that  these  are  satisfactory  methods  of  making  a  drill  cut  larger.  It 


DRILLS  AND  DRILLING 


117 


may  be  permissible  in  an  emergency  to  slightly  enlarge  a  hole  by  grind- 
ing the  point  eccentric,  but  the  result  is  generally  disappointing,  as 
the  hole  is  very  likely  to  be  irregular  and  rough. 

Straight-shank  Twist-drills. — The  drill  shown  in  Fig.  154  has  a 
taper  shank  designed  to  fit  into  a  taper  hole  in  the  end  of  the  drill- 
spindle.  Fig.  165  differs  from  the  latter  only  in  the  form  of  the  shank, 


FIG,   165. 

which  is  straight.  The  straight  shank  is  designed  to  be  driven  by  a 
chuck  which  screws  on  the  drill-spindle. 

Twist-drills  are  also  made  with  "taper-square  shanks."  These  are 
designed  to  be  used  with  a  ratchet. 

Three-groove  and  Four-groove  Drills. — Figs.  166  and  167  show 
respectively  a  three-groove  and  a  four-groove  twist-drill.  These  drills 


FIG.  166. 


FIG.  167. 

cannot  be  used  to  drill  holes  from  the  solid.  In  drilling  very  large 
holes  many  mechanics  prefer  to  use  two  drills.  The  first,  a  two-groove 
drill,  makes  the  hole  about  half  the  size.  This  is  followed  by  a  three- 
groove  or  four-groove  drill.  The  latter  are  also  used  to  enlarge  cored 
holes.  It  is  not  considered  advisable  to  use  the  two-groove  drill  in 
cored  holes.  When  used  in  the  lathe  to  slightly  enlarge  a  hole  the 
two-groove  drill  tends  to  "draw  in." 

Straightway  or  Farmer  Drills. — The  twist-drill  is  by  far  the  most 
important  drill  used  in  the  machine-shop;  we  are,  therefore,  giving 
it  the  most  space,  and  shall  refer  to  it  again  in  connection  with  the 
subject  of  "deep  drilling."  The  Farmer  drill  (Fig.  168)  differs  from 
the  twist-drill  in  that  the  grooves  are  straight  and  parallel  with  the 
axis  of  the  drill  rather  than  helical.  The  twist-drill  presents  an  inclined 


118 


MACHINE-SHOP  TOOLS  AND  METHODS 


cutting  edge  to  the  metal,  and  peels  the  metal  very  much  the  same 
as  a  plow  turns  over  the  soil;  and,  as  was  stated,  the  helical  form 
tends  to  screw  the  chips  out  of  the  hole.  The  Farmer  drill  lacks  this 
principle,  and  while  it  will  not  cut  so  rapidly  and  freely  as  the  twist- 
drill,  it  has  some  advantages  in  drilling  holes  for  slots  and  in  drilling 
sheet  metal  and  brass.  In  drilling  brass  the  twist-drill  tends  to  advance 
faster  than  the  rate  of  feed,  and  thus  sometimes  gouges  into  the  metal. 


FIG.  168. 

This  tendency  is  particularly  noticeable  when  the  point  of  the  drill  is 
emerging  through  the  bottom  of  the  hole.  No  such  difficulty  occurs 
in  the  use  of  the  Farmer  drill.  When  drilling  sheet  metal  the  Farmer 
drill  does  not  tend  to  lift  the  sheet  as  does  the  twist-drill,  and  in  drilling 
holes,  to  save  excessive  chipping  in  making  slots,  the  holes  may  be 
drilled  somewhat  closer,  leaving  less  work  for  the  chisel  than  would  be 
necessary  if  the  twist  drill  were  used.  Notwithstanding  the  advantages 
of  the  Farmer  drill  in  certain  kinds  of  work,  it  is  not  so  efficient  a  tool 
as  the  twist-drill.  The  instructions  for  grinding  the  twist-drill  apply 
equally  well  to  the  straightway  drill. 

The  Flat  Drill. — Some  one  has  said  that  the  flat  drill  "has  the  faculty 
of  drilling  holes  that  are  neither  round  nor  straight,  and  whose  diameter 
seems  to  bear  no  relation  to  the  diameter  of  the  drill."  This  is  a  rather 
strong  statement  of  the  fact  that  the  flat  drill,  as  ordinarily  made,  can- 
not be  relied  on  for  accurate  work.  Fig.  169  shows  the  typical  form 


FIG.  169. 

of  flat  drill.  In  its  crudest  shape  it  may  be  made  altogether  in  the  forge- 
shop  at  very  small  expense.  It  consists  of  a  bar  of  steel  flattened 
out  and  made  V-shaped  at  the  cutting  end,  which  end  is  ground  for  clear- 
ance the  same  as  a  twist-drill.  The  bar  is  tapered  on  the  shank  end; 
generally  to  fit  a  square  tapered  socket.  The  flat  drill  was  formerly 
used  for  all  general  work,  but  it  has  now  been  almost  entirely  superseded 
by  the  twist-drill.  If  one  needs  a  special  size  of  drill  in  an  emergency,  a 
flat  drill  could  be  very  quickly  made  for  the  purpose.  The  flat  drill 


DRILLS  AND  DRILLING 


119 


is  also  used  to  some  extent  in  connection  with  the  small  drilling  device 
called  ratchet-drill.  By  machining  the  flat  drill,  giving  it  nearly  parallel 
sides  and  a  round  shank,  it  may  "be  made  to  do  fairly  good  work ;  but 
even  in  its  best  shape  it  will  not  gpmpare  favorably  with  the  twist-drill. 
The  Pin-drill,  or  Counterbore. — Most  of  the  drills  above  described 
are  designed  to  originate  holes,  that  is,  to  drill  holes  from  the  solid. 
The  pin-drill,  illustrated  in  Fig.  170,  is  never  used  for  this  purpose.  Its 


FIG.  170. 

principal  use  is  that  of  counterboring  holes  for  round-head  screws.  For 
this  reason  it  is  often  called  a  counterbore.  It  may  be  used  also  for 
enlarging  holes  previously  drilled,  and  for  facing  small  bosses  to  make 
a  true  bearing  for  nuts  and  heads  of  bolts.  It  is  sometimes  made  with 
bevel  cutting  edges,  as  in  Fig.  171,  for  countersinking  holes  for  bevel- 


FIG.  171. 

head  screws.     In  using  the  pin-drill  the  pin  end  G,  Fig.  170,  fits  in,  and 
is  guided  by,  the  hole. 

The  form  shown  in  Fig.  171  can  be  used  for  one  size  of  hole  only, 
and  for  one  size  of  counterbore,  but  a  pin-drill  may  be  made  with  both 
pin  and  cutter  adjustable  for  different  sizes  of  holes.  Fig.  172  shows  such 


FIG.  172. 

a  tool.  The  cutter  C  is  held  in  a  slot  in  the  bar.  The  pin  or  guide  P 
is  detachable,  and  the  different  sizes  are  held  by  the  screw  S.  This  tool 
is  more  appropriately  called  a  counterbore.  Fig.  173  shows  another 
method  of  making  a  counterbore. 


120 


MACHINE-SHOP  TOOLS  AND  METHODS 


Form  and  Use  of  the  Tit-drill.  Bottoming-drills.  —  If  we  wish  to 
drill  a  hole  that  does  not  pass  through  the  metal,  the  bottom  of  the  hole 
will  be  conical  in  shape  if  made  by  any  of  the  drills  previously  described. 


FIG.  173. 

If  we  wish  the  bottom  of  the  hole  approximately  flat,  we  use  the  tit-drill 
shown  in  Fig.  174.  This  drill  is  in  principle  the  same  as  the  flat  drill, 
the  difference  being  that  in  the  tit-drill  the  beveled  point  is  reduced  to 
a  minimum.  If  we  wish  to  make  the  bottom  of  the  hole  perfectly  flat, 
we  use  a  drill  without  the  little  beveled  point,  which  drill  is  called  a 
bottoming-drill,  see  Fig.  175.  The  tit-drill  will  originate  a  hole,  but  the 


FIG.  174. 


FIG.  175. 


bottoming-drill  must  be  preceded  by  some  other  form  of  drill;  or  the  hole 
must  be  at  least  started,  so  as  to  form  a  guide  for  the  drill  on  its  sides. 
The  lips  or  cutting  edges  of  the  tit-  and  bottoming-drills  are  ground 
on  the  same  general  principles  as  the  twist-drill. 

Slotting-drills. — This  drill  is  illustrated  in  Fig.  176.     As  indicated 
by  its  name,  it  is  designed  for  slots  or  oblong  holes.     It  will  make  a 


FIG.  176. 

slot  independently  of  chisel  or  file,  but  to  use  the  drill  the  machine  in 
which  it  is  used  must  be  provided  with  means  of  feeding  either  the 
drill  or  the  work  lengthwise  of  the  slot.  It  is  well  to  drill  a  hole  equal 


DRILLS  AND  DRILLING 


121 


to  width  of  slot  with  twist-drill  or  tit-drill,  to  give  the  slotting-drill  a 
start.  It  may  then  be  fed  lengthwise  of  the  slot,  and  downward  about 
Vie  to  J/4  mcn  at  each  end,  until  the  slot  is  the  required  length  and 
depth.  The  slot  will  be  semicircular  at  each  end,  which  is  all 
right  hi  many  cases;  but  if  required  to  be  square,  it  may  be  made 
so  with  chisel  and  file.  This  method  of  making  slots  is  not  employed 
to  any  great  extent,  and  the  drill  is  largely  superseded  by  the  end 
mill.  (See  under  Milling-machines.) 

Oil-tube  Drills.  Deep  Drilling. — In  drilling  holes  of  ordinary  depth, 
say  1  to  4  inches,  if  a  lubricant  is  needed  it  may  be  applied  by  a  com- 
mon oil-can.  But  for  holes  more  than  about 
4"  an  oil-tube  drill  will  be  advantageous. 
This  may  be  made  in  the  form  of  a  common 
twist-drill  having  grooves  milled  into  the 
clearance  surface  of  the  body  into  which 
small  tubes  are  soldered.  These  tubes  ex- 
tend the  whole  length  of  the  drill  proper, 
and  open  into  a  kind  of  collar  near  the 
shank  end  of  the  drill.  Connected  with  this 
collar  is  a  pipe  (sometimes  a  flexible  tube) 
leading  to  the  source  of  oil-supply,  which  is 
frequently  a  pump.  The  collar  is  a  running 
fit  on  the  drill,  and  is  held  stationary  while 
the  latter  turns.  This  description  holds  good 
when  the  drill  is  used  in  an  upright  drilling- 
machine.  Such  a  machine  is  shown  in  Fig. 
177,  in  which  C  is  the  collar  and  E  the  pipe 
or  hose  leading  to  the  oil-pump.  The  Morse 
Twist-drill  and  Machine  Company  drill  oil- 
holes  in  drills  less  than  21/2"  diameter,  and 
use  the  oil- tubes  in  the  larger  sizes.  Fig. 
178  shows  a  drill  with  oil-holes.  These 
holes  are  drilled  in  blanks  which  are 
milled. 

For  deep  drilling  in  the  lathe  the  drill  may  be  made  like  Fig.  179, 
or  the  oil-hole  may  pass  through  the  shank  at  its  end,  as  in  Fig.  180. 
A  drill  made  like  Fig.  180  is  shown  in  operation  hi  Fig.  181.  The  oil- 
pump  is  worked  automatically  by  mechanism  attached  to  the  lathe. 
The  pump  is  connected  with  an  oil-tank  into  which  the  waste  oil  returns 
through  a  strainer. 


FIG.  177, 


afterward     twisted    and 


122 


MACHINE-SHOP  TOOLS  AND  METHODS 


In  extra-deep  drilling  sometimes  a  steel-tube  extension  is  secured 
to  the  end  of  a  short  oil-hole  drill.  This  combination  is  probably 
cheaper  than  a  drill  of  the  required  length. 


FIG.  178. 


It  is  essential  in  deep  drilling  that  the  hole  be  made  the  required 
diameter,  several  inches  deep,  before  the  special  drill  is  started.    This 


FIG.  179 

preliminary  work  may  be  done  with  a  regular  twist-drill  and  boring- 
tool,  the  latter  being  used  to  "true  up"  the  hole. 


FIG.  180. 

The  twist-drill  is  by  no  means  the  only  form  of  drill  used  for  deep 
holes.     Indeed,  some  mechanics  think  it  is  not  equal  to  a  one-lip  drill 


-  FliXlBLE  TU§IN<5  TO  PUMP 


FIG.  181. 

when  the  most  accurate  work  is  needed.     The  one-lip  drill,  however, 
is  rather  slow  hi  operation. 


DRILLS  AND  DRILLING  123 

For  a  more  comprehensive  discussion  of  the  subject  of  deep  drilling, 
and  of  tools  for  the  purpose,  the  reader  is  referred  to  articles  in 
"Machinery,"  published  in  December  1901  and  January  1904. 

Lubricants  Used  in  Drillingji*-Cast  iron,  brass,  and  Babbitt  metal 
may  be  drilled  without  any  lubricant.  In  drilling  steel,  oil  should 
be  used;  in  drilling  soft  steel  and  wrought  iron  we  use  either  oil  or  a 
mixture  made  of  sal-soda  and  water.  A  drilling  compound  may  be 
purchased  for  this  purpose.  It  is  economical  to  use  the  mixture  when 
there  is  considerable  drilling  to  be  done,  but  for  a  few  holes  a  common 
oil-can  is  more  convenient.  If  required  to  drill  glass,  we  use  kerosene 
oil  or  turpentine,  the  latter  being  preferable. 

Speed  of  Drills. — There  is  considerable  variation  in  practice  respect- 
ing the  speed  of  drills.  The  following  formulas  are  suggested  as  an 
approximation  to  average  practice: 

100  125  225 

for  machine  steel  R.P.M.  =  -JT-;   for  cast  rron=-^r-;   for  brass  =  -7p 

where  D  equals  diameter  of  drill  in  inches  and  R.P.M.  the  number  of 
revolutions  per  minute.  The  peripheral  speeds  corresponding  to  the  above 
are  (nearly)  26,  33,  and  60  feet  per  minute.  The  formulas  assume  the 
same  peripheral  speed  for  large  and  small  drills.  This  rule  is  in  accord- 
ance with  the  practice  of  one  of  the  leading  drill-manufacturers,  and  it 
will  answer  for  90  per  cent  of  the  drills  used.  But  for  the  exceptionally 
large  drills  it  may  be  necessary  to  run  somewhat  slower.  As  indicating 
the  allowable  difference  in  speeds  of  large  and  small  drills,  the  follow- 
ing is  taken  from  the  table  of  speeds  given  by  one  of  the  oldest  drill- 
makers:  R.P.M.  for  74"  =565;  for  i/2"=267;  for  3/4//  =  168,  and 
for  1"  =  115.  These  speeds  are  for  cast  iron,  and  it  will  be  seen  that 
the  speed  of  the  V*"  drill  is  nearly  five  times  that  of  the  1"  drill. 

It  is  the  usual  practice  in  turret-machine  work — excepting  cast  iron — 
to  keep  the  drill  flooded  with  oil.  Under  such  conditions  the  speed  may 
be  much  higher. 

The  above  rules  should  be  used  with  discrimination  and  good  judg- 
ment. If  any  of  the  materials  be  exceptionally  hard  or  the  drill  heat 
too  much,  a  slower  speed  may  be  necessary.  It  may  be  remarked  in 
this  connection  that  a  drill  will  heat  with  moderate  speed  when  the 
body  clearance  near  the  lips  has,  by  improper  usage,  been  destroyed. 

"  High-speed  Steel "  for  Drills. — Within  the  last  few  years  a  new 
steel,  known  by  the  general  name  of  "  high-speed  steel,"  has  been  placed 
upon  the  market.  There  are  a  number  of  different  varieties,  varying 
slightly  in  chemical  composition,  the  price  being  from  three  to  five 


124  .  MACHINE-SHOP  TOOLS  AND  METHODS 

times  that  of  ordinary  steel.  This  steel  is  scarcely  out  of  the  experimen- 
tal stage,  and  it  does  not  seem  to  have  met  with  the  same  degree  of  suc- 
cess in  drills  that  it  has  when  made  into  lathe-tools.  Nevertheless  a  drill 
made  of  this  steel  may  be  run  about  twice  as  fast  as  the  speeds  indicated 
above  for  common  steel. 

Drill-feeds. — The  Morse  Twist-drill  and  Machine  Company  recommend 
feeds  of  .005",  .007",  and  .010"  for  1/4",  i/2",  and  3/V'  drills  respectively. 
As  in  the  speeds,  so  also  in  respect  to  the  feeds  good  judgment  on 
the  part  of  the  operator  is  necessary.  In  drilling  soft  materials,  such 
as  Babbitt  metal,  brass,  and  extra-soft  cast  iron  the  above  feeds  may  be 
materially  increased.  In  this  connection  the  attention  of  the  reader 
is  called  to  what  was  said  respecting  feeds  in  the  chapter  on  Drilling- 
machines. 

Drilling  Hard  Metal. — In  drilling  exceptionally  hard  steel  or  other 
hard  metal,  the  surface  will  sometimes  glaze  under  the  pressure  of  the 
drill.  Oil  as  ordinarily  used  aggravates  this  difficulty,  and  the  cutting 
edges  of  the  drill  should  be  barely  moistened  with  oil.  As  often  as  the 
surface  glazes  it  should  be  roughed  up  by  indenting  it  with  a  narrow- 
pointed  chisel.  This  is  of  more  value  than  oil. 

If  a  twist-drill "  chip  off"  at  the  cutting  edges  when  drilling  hard  metal, 
the  fronts  of  the  cutting  edges  may  be  flattened  slightly  by  grinding. 
This  is  sometimes  done  when  drilling  brass.  The  object  in  this  case  is 
not  to  prevent  chipping  off,  but  to  overcome  the  tendency  of  the  drill 
to  "hog  in."  It  will  be  explained  under  Lathe-tools  that  a  tool  with 
front  or  top  rake  is  more  likely  to  dig  in  when  cutting  brass  than  in 
cutting  any  other  metal.  Flattening  the  drill  cutting  edge  in  a  plane 
parallel  with  its  axis  neutralizes  the  rake» 


CHAPTER  IX 
DRILL-SOCKETS,  DRILL-CHUCKS,  AND  ACCESSORIES 

THE  spindles  of  most  drilling-machines  have  a  tapering  hole  in  one 
end  to  receive  the  tapering  shank  of  the  drill.  At  the  bottom  of  the 
tapering  hole  is  a  slot  with  which  the  tang  (or  tongue)  of  the  drill  engages. 
This  is  the  most  common  method  of  driving  drills.  The  proportions  of 
the  tapers  for  this  purpose  usually  conform  to  the  Morse  standard, 
which  is  approximately  5/8"  per  foot.  There  are  six  sizes  of  shanks  in 
the  Morse  system.  The  various  dimensions  for  these  are  given  in  a 
table  in  connection  with  Fig.  189  at  the  end  of  this  chapter. 

Drill-sockets. — As  the  drill-spindle  can  be  made  to  fit  only  one  size 
of  shank,  the  smaller  sizes  of  drills  are  driven  by  sockets.  One  end  of 
the  socket  fits  the  spindle,  and  the  other  end  fits  the  drill-shank. 
Fig.  182  shows  the  ordinary  drill-socket,  and  Fig.  183  a  key  used  for 


FIG.  182. 

driving  out  the  drill  and  also  for  driving  the  socket  out  of  the  spindle. 
The  key  enters  the  socket  through  the  slot  shown. 

Abuse  of  Drill-sockets.  Positive  "  Grip-sockets." — The  drill-shank 
should  fit  a  socket  like  the  one  described  so  accurately  that  it  would 
be  driven  partly  by  friction.  But  in  the  hands  of  careless  workmen 
the  socket,  and  often  the  shank,  are  damaged  so  that  the  fit  of  the 
taper  is  disturbed.  The  barbarous  practice  of  hammering  the  socket 
off  when  the  key  is  misplaced  causes  most  of  this  damage. 

When  the  socket  has  been  pounded  out  of  shape  the  drill-shank 
fails  to  go  into  the  socket  the  full  depth,  and  the  tang  works  at  a  dis- 
advantage. The  drill  runs  out  of  true,  also.  If  now  the  drill  hang 
in  a  blow-hole,  or  catch  while  its  point  is  emerging  through  the  bottom 

125 


126  MACHINE-SHOP  TOOLS  AND  METHODS 

of  the  drilled  hole,  the  framework  of  the  machine  may  be  sprung  to 
such  an  extent  as  to  cause  the  socket  to  lift  and  "ride"  the  tang  of  the 


FIG.  183 


drill.     This  destroys   both   the   tang  and   the  slot  in   the  socket.     In 
some  cases  the  tang  is  twisted  off.     When  one  has  a  number  of  drills 


FIG.  184. 


with  broken  tangs  it  may  pay  to  purchase  one  or  more  sockets  like 
that  shown  in  Fig.  184. 


DRILL-SOCKETS,  DRILL-CHUCKS,  AND  ACCESSORIES 


127 


A  drill  to  be  used  in  this  socket  must  have  a  groove  milled  in  its 
shank  as  in  Fig.  185.  The  shank  of  the  socket  has  a  similar  groove, 
in  order  that  it  may  be  driven  in  a  .similar  manner.  The  collar  C  on  the 
end  of  the  socket  is  counterbored  eccentrically.  When  turned  forward 
it  forces  the  key  K  into  ihe  groo^  of  the  drill-shank.  Turning  it  in 
the  opposite  direction  releases  the  drill. 

A  Cheap  Device  for  Driving  Broken-tang  Drills. — A  much  cheaper 
though  not  so  convenient  a  device  may  be  made  as  follows :  Get  a  cast- 
iron  or  steel  collar  about  3"  long  and  bore  it  out  to  closely  fit  the  large 


end  of  the  drill-socket  shown  in  Fig.  182.  Drill  and  tap  for  two  set- 
screws  near  each  end  of  the  collar.  The  set-screws  at  one  end  should 
be  pointed  to  fit  conical  seats  drilled  about  Vie"  deep  in  the  socket. 
The  other  two  set-screws  drive  the  drill  by  gripping  in  the  flutes  near 
the  shank.  For  drill-press  work  headless  set-screws,  which  do  not 
project  beyond  the  periphery  of  the  collar,  should  be  used.  If  the  collar 
be  held  stationary  in  lathe  work,  square-head  set-screws  may  be  used 
without  endangering  the  workman.  A  driving  device  of  this  kind  does 
not  require  that  the  drill-shank  be  grooved,  as  the  set-screws  drive 
by  the  grooves  already  made  in  the  drill. 

If  the  socket  to  be  used  with  this  device  has  been  damaged  by 
hammer-blows,  it  should  be  carefully  " trued  up"  before  the  collar  is 
fitted.  The  drill-shanks  also  may  need  attention. 


128 


MACHINE-SHOP  TOOLS  AND  METHODS 


Drill-chucks. — Fig.  186  shows  a  drill-chuck  designed  for  driving 
straight-shank  drills  by  friction.  The  jaws  J  are  caused  to  grip  or 
release  the  drill  by  the  right-  and  left-threaded  screw  S.  This  screw 
is  operated  by  a  key  K  which  fits  the  square  hole  in  its  end. 


FIG.  186. 

The  chuck  is  usually  fitted  to  an  arbor  which  has  a  taper  shank 
fitting  the  drill-spindle. 

Fig.  187  shows  a  chuck  in  which  the  grip  of  the  jaws  is  assisted  by 
a  special  tang  on  the  drill  fitting  the  rectangular  opening  at  T.  This 
chuck,  also,  drives  straight-shank  drills  only.  The  chuck  method  is  well 
adapted  to  the  smaller  sizes  of  drills. 

Lathe  Drill-sockets. — Drills  are  sometimes  driven  in  the  lathe  by 
a  chuck  on  the  revolving  spindle,  but  the  ordinary  method  is  to  hold 
the  drill  stationary  while  the  work  revolves.  In  this  case  the  shank 
end  of  the  drill  is  supported  by  the  tail-spindle  center,  the  other  end 


DRILL-SOCKETS,  DRILL-CHUCKS,  AND  ACCESSORIES 


129 


being  supported  by  the  .  hole  in  the  work.  To  keep  the  drill  from 
turning  a  " lathe-socket'' — also  called  a  " drill-holder" — is  used.  Fig. 
188  shows  such  a  tool.  The  taper  shank  of  the  drill  fits  the  socket  of 


MADE  BY 
PRATT  CHUCK  CP- 

FRANKFORT 


FIG.  187. 


FIG.  188. 

the  holder,  while  the  long  arm  rests  on  the  lathe  as  shown,  or  on  a  tool 
in  the  lathe  tool-post.  In  the  latter  case  the  tool-post  is  sometimes 
brought  up  against  the  arm  in  such  a  manner  that  the  pressure  required 


130 


MACHINE-SHOP  TOOLS  AND  METHODS 


to  feed  the  drill  moves  the  lathe-carriage  in  the  same  direction.  The 
object  of  this  is  to  prevent  the  drill  from  drawing  in  ahead  of  the  feed, 
as  it  is  likely  to  do  under  some  conditions. 

The  steady  rest  R  shown  in  the  illustration  is  not  essential  in  such 
work.  It  is,  however,  advantageous  where  a  large  quantity  of  work 
of  one  kind  is  to  be  drilled.  The  ordinary  method  is  to  start  the  drill 
in  a  conical  center  cut  in  the  work.  This  center  is  made  by  a  V-pointed 
tool  held  in  the  tool-post.  (See  Fig.  376.) 

MORSE  TAPER  SHANKS 


'£ 


r 

T            ~r 

I 

g 

V 

5, 

Fie.  189. 
DIMENSIONS 

No. 

A 

B 

c 

D 

E 

Taper 
in  12  in. 

1 

2& 

2| 

.356 

.475 

u 

.600 

2 
3 

3^ 

3! 

| 

.556 
.759 

.700 
.938 

A 

602 
.602 

4 

4 

4 

.997 

1.231 

ft 

.623 

5 

6 

5f 

1.446 

1.748 

I 

.630 

6 

8& 

8 

2.077 

2.494 

I 

.626 

The  best  drill-holders  are  those  having  one  closed  end  with  an  extra 
large  center  reamed  in  this  end.  In  using  those  having  both  ends  open, 
the  drill  is  supported  by  the  center  in  its  tang.  As  the  tang  is  rather 
thin  in  some  sizes,  the  center  sometimes  breaks  through. 

The  Lathe-dog  as  a  Drill-holder.  Split  Sleeves. — A  lathe-dog  can 
be  used  as  a  drill-holder,  but  a  conscientious  workman  will  not  do  this 
if  it  can  possibly  be  avoided.  The  set-screw  cuts  into  and  raises  lumps 
on  the  shank.  This  destroys  its  fit  in  the  socket  and  makes  the  drill 
run  "out  of  true."  It  may  also  cause  the  trouble  with  the  tang  pre- 
viously mentioned.  If  a  straight-shank  drill  be  used,  the  set-screw 
bruises  may  affect  its  concentricity  when  used  in  the  chuck. 

If  a  drill  must  be  held  with  a  lathe-dog,  its  shank  should  be  protected. 
A  cast-iron  collar  bored  to  fit  the  shank  and  sawed  through  on  one  side 


DRILL-SOCKETS,  DRILL-CHUCKS,  AND  ACCESSORIES          131 

would  answer  the  purpose  very  well.  The  set-screw  of  the  lathe-dog 
would  cause  the  collar  to  tightly  grip  the  drill-shank  without  injuring  it. 

A  thin  steel  sleeve  cut  through  on  one  side  is  often  used  on  the  taper 
shank  of  a  broken-tang  drill  which  is  to  be  driven  by  a  drill-chuck; 
otherwise  straight-shank  drills  onl^  are  driven  in  chucks.  The  sleeve 
being  tapering  in  the  hole  and  straight  on  the  outside,  makes  the  taper 
shank  in  effect  the  same  as  a  straight  shank.  Another  way  of  adapting 
the  taper  shank  to  the  chuck  is  to  turn  it  straight  in  the  lathe. 

A  Hazardous  Practice. — Some  workmen  get  into  the  habit  of  taking 
the  drill  out  and  putting  it  back  while  the  lathe  is  running.  This  is 
taking  chances  of  the  unsupported  drill  hanging  and  smashing  both 
the  drill  and  the  workman's  fingers. 


CHAPTER  X 
CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS 

Drills  and  Reamers  Compared. — The  twist-drill,  which  is  reliable 
enough  for  most  bolt-holes,  clearance-holes,  etc.,  cannot  be  depended 
upon  to  make  holes  sufficiently  smooth  and  accurate  for  such  work  as 
shaft-bearings,  gears,  and  many  other  machine  details.  There  are  two 
reasons  for  this:  first,  it  is  difficult  to  so  grind  the  drill  as  to  make  it 
cut  exactly  its  own  size;  second,  the  drill  being  tapering,  its  diameter 
is  a  variable  quantity,  as  has  already  been  explained  under  the  subject 
of  "  Drills  and  Drilling."  The  construction  of  the  reamer,  however, 
is  such  as  to  obviate  in  a  large  measure  these  irregularities.  The  prin- 
cipal reason  for  the  reamer  doing  better  work  than  the  drill  is  that  it 
is  not  used  to  originate  holes,  and  its  action  is,  therefore,  not  dependent 
upon  a  somewhat  uncertain  guiding-point.  Other  reasons  are  that  it 
nearly  always  has  more  than  two  cutting  edges,  and  when  properly  used 
should  have  very  little  metal  to  remove.  Those  tools  called  roughing- 
reamers  and  some  chucking-reamers,  which  do  remove  a  much  larger 
quantity  of  stock,  should,  in  the  judgment  of  the  author,  be  called  bits. 

Definition  and  Classification  of  Reamers. — It  would  be  difficult  to 
give  a  concise  definition  of  reamer  were  we  to  include  all  of  the  non- 
descript tools  that  mechanics  have  crowded  under  that  head.  Properly 
speaking,  a  reamer  may  be  defined  as  a  tool  for  perfecting  holes  previ- 
ously drilled  or  bored.  Fig.  190  shows  a  standard  famd-reamer.  This 


FIG.  190. 

reamer  should  never  be  used  to  remove  any  considerable  quantity  of 
stock,  but  merely  to  eliminate  minute  imperfections  left  by  other  tools, 
and  to  bring  the  hole  to  some  exact  and  definite  diameter.  In  some 

132 


CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS  133 

cases  the  hole  may  be  made  to  within  .001"  before  the  reamer  is  applied; 
but  generally  an  allowance  of  .002"  to  .010",  according  to  the  diameter 
of  the  hole,  may  be  left  for  the  standard  reamer  to  cut.  If  given  too 
much  metal  to  remove,  the  cutting  edges  of  the  reamer  will  wear  too 
fast,  and  its  reliability  as  a  sizer  will  be  too  quickly  destroyed. 

Reamers  may  be  divided  into  the  two  general  classes  of  side-cutting 
or  fluted  reamers,  and  end-cutting  reamers  or  bits.  Each  of  these 
clases  are  subdivided  into  solid  and  adjustable  reamers. 

The  Solid  Fluted  Reamer. — This  reamer  is  made  with  slight  modifi- 
cations suiting  the  two  different  cases  for  both  hand  and  machine  use. 
The  hand-reamer  of  Fig.  190  belongs  to  the  "  short  "  set.  Reamers  of  the 
same  general  design  are,  also,  made  longer  in  regular  sets,  and  will  be 
made  to  order  of  special  lengths.  The  cutting  edges  of  fluted  reamers 
are  made  tapering  in  diameter  for  about  one  fourth  their  length  from  A 
toB,  being  about  .01"  smaller  at  A  than  at  B.  From  B  to  C  the  taper  is 
reversed,  the  diameter  decreasing  toward  C  at  about  .0002"  per  inch  of 
length.  That  part  of  the  shank  between  D  and  E  is  usually  made  about 
.001  smaller  than  the  largest  diameter  at  B.  When  the  cutting  edges 
are  worn  to  such  an  extent  that  this  blank  part  when  free  from  bruises 
will  not  pass  through  the  reamed  hole,  the  reamer  is  too  small  for  standard 
holes. 

As  will  be  seen,  the  hand-reamer  has  a  square  end,  upon  which  a 
wrench  is  used  to  turn  the  reamer.  This  is  the  main  distinguishing 
feature  between  this  reamer  and  the  machine-reamer  of  the  fluted  form. 
The  latter  is  made  with  taper  and  parallel  shanks  the  same  as  a  drill. 
It  may  also  have  a  shank  of  any  special  shape  to  fit  a  special  holder. 
The  machine-reamer  is  generally,  though  not  always,  made  straight  or 
parallel  from  A  to  B.  Fig.  191  shows  a  taper-shank  reamer  of  the  above 
class. 

B  A 


FIG.  191. 

Spirally  Fluted  Reamers. — Reamers  having  the  flutes  parallel  with 
the  axis  have  a  slight  tendency  to  "draw  in."  To  overcome  this, 
some  mechanics  prefer,  for  both  hand  and  machine  work,  reamers  having 
flutes  in  the  form  of  a  left-hand  spiral.  The  angle  of  the  spiral  or  helix 
may  be  from  4  to  8  degrees.  The  author  of  this  book  makes  spiral 
reamers  of  6°  angle,  but  within  reasonable  limits  the  degree  of  angularity 
is  of  little  importance. 


134 


MACHINE-SHOP  TOOLS  AND  METHODS 


Rose-reamers.  Rose  and  Fluted  Reamers  Compared. — The  rose- 
reamer,  or  rose-bit,  derives  its  name  from  the  slight  resemblance  of  its 
cutting  end  to  a  rose.  It  is  essentially  an  end-cutting  tool,  and  is 
rarely  used  for  other  than  machine-work.  Fig.  192  shows  a  rose-reamer 


FIG.  192. 

of  typical  form.  It  has  chip-  and  oil-grooves  on  the  sides,  and  is  made 
with  any  shank  required  in  machine-work.  This  reamer  is  largest  in 
diameter  at  its  cutting  end,  and  tapers  back  at  about  the  same  rate  as 
the  hand-fluted  reamer,  viz.,  .0002"  per  inch  of  length. 

The  object  of  the  taper  (i.e.,  the  taper  toward  the  shank)  on  the 
fluted  reamer  is  to  counteract  the  tendency  of  all  such  reamers  to  ream 
the  hole  larger  at  the  entrance  end.  In  the  rose-reamer  the  taper  is 
given  for  the  same  reason  we  give  taper  to  the  twist-drill,  viz.,  for 
clearance. 

As  compared  with  the  fluted  reamer,  the  rose-reamer  has  the  advan- 
tage that  when  new  it  will  make  holes  more  uniform  in  size  and  more 
nearly  straight;  but  it  has  the  disadvantage  that  when  it  becomes 
worn  on  the  cutting  lips  it  will  bind  on  the  sides  and  " rough  up"  the 
holes.  If  the  fluted  reamer  become  slightly  worn  at  the  end,  it  will 
still  cut  on  the  sides;  but  because  of  its  cutting  on  the  sides  it  is  more 
likely  to  be  deflected  by  imperfections  in  the  hole,  or  to  cut  larger  than 
its  nominal  size. 

As  previously  stated,  the  standard  fluted  reamer  should  be  used  for 
finishing  cuts  only,  but  the  rose-reamer  is  used  for  both  finishing  and 
roughing  cuts.  However,  when  the  same  reamer  is  used  for  both 
purposes  it  soon  becomes  unreliable  as  a  standard  finishing-tool. 

Shell-reamers.— Figs.  193  and  194  show  respectively  a  fluted  shell- 


FIG.  193 


FIG.  194. 


reamer  and  a  rose  shell-reamer,  and  Fig.  195  shows  the  arbor  for  these 
reamers.     The  arbor  drives  the  shell  by  the  engagement  of  its  key  with 


CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS  135 

the  rectangular  slot  cut  across  the  end  of  the  shell.     These  reamers  are 
made  with  either  straight  or  spiral  flutes. 

It  will  be  understood  that  £he  object  of  making  the  reamers  in  the 
shell  form  is  economy  in  the  co|f  of  material.  One  arbor  of  machine- 
steel  will  serve  for  several  shells  of  tool-steel.  It  should  be  noted,  how- 
ever, that  the  saving  due  to  cheap  material  in  the  arbors  is  partly  offset 


FIG.  195. 

by  the  expense  incident  to  boring  the  shell  and  fitting  the  end  of  the 
arbor  to  it. 

The  shells  as  ordinarily  made  are  rather  short  for  hand-reaming, 
being  designed  mainly  for  machine- work.  The  taper  begins  at  the 
cutting  end,  and  the  diameter  decreases  toward  the  opposite  end  in 
about  the  same  ratio  as  the  reamers  previously  described. 

Resetting  Fluted  and  Rose  Reamers. — When  these  reamers  wear 
.0003  to  .001  inch  below  standard  size  it  is  necessary  to  reset  them,  or 
regrind  them  to  a  smaller  size.  Resetting  consists  in  enlarging  the 
diameter  of  the  reamer  by  hammer-blows  in  connection  with  a  kind 
of  set  or  calking-tool.  The  latter,  which  may  be  made  by  grinding  a 
common  chisel  flat  on  the  end,  is  held  against  the  front  of  the  cutting 
edges  for  this  purpose.  It  is  necessary  to  anneal  the  reamer  for  resetting, 
and  each  cutting  edge  must  be  treated  until  the  diameter  is  about  Vw" 
larger  than  standard.  Having  completed  this  work  the  reamer  is  now 
retempered  and  brought  to  final  size  in  the  universal  grinder. 

Lapping  Reamer-centers. — Before  grinding  the  reamer  its  centers 
should  be  carefully  cleaned  of  any  grit  or  other  foreign  matter  that 
may  have  adhered  to  them  in  the  forge.  A  pointed  scraper  made  from 
a  three-cornered  file  answers  well  for  this.  After  scraping  the  centers 
it  is  usually  necessary  to  lap  them.  For  this  process  we  chuck  a  short 
brass  rod  in  the  lathe,  and  turn  the  end  to  the  shape  of  the  lathe-centers. 
Having  smeared  this  conical  end  with  fine  emery  and  oil,  the  reamer 
is  placed  on  the  centers  and  the  lathe  started  on  the  fastest  speed.  The 
reamer-center  is  lapped  by  alternately  forcing  it  against  and  releasing 
it  from  the  revolving  brass.  This  is  done  by  light  pressure  with  the 
tail-spindle,  and  for  each  time  that  the  reamer  is  pressed  against  the 
brass  it  should  be  revolved  slightly.  By  thus  revolving  it  we  distribute 
the  emery  and  counteract  the  tendency  of  the  lap  to  scratch  rings  in  the 


136 


MACHINE-SHOP  TOOLS  AND  METHODS 


center.  It  is  sometimes  necessary  to  re-turn  the  lap  before  finishing 
one  reamer;  but  a  skillful  workman  can  do  this  in  ten  minutes  or  less. 

Instead  of  having  to  chuck  the  lap  each  time  it  is  used,  it  would  be 
better  to  make  one  to  fit  the  hole  in  lathe-spindle. 

Adjustable  Reamers. — From  a  consideration  of  the  difficulties  of 
resetting  or  upsetting  the  solid  reamers  the  advantages  of  the  adjust- 
able reamer  will  be  apparent.  While  some  reamers  of  this  class  will 
admit  of  as  much  as  1/32//  enlargement ,  the  object  of  the  adjustment 
is  not  so  much  to  make  different  sizes  of  holes  as  to  compensate  for  wear 
and  thereby  maintain  standard  sizes.  Figs.  196  and  197  show  sectional 

Blades 


^Clamping  nut 

P=  Adjusting  plug 


FIG.   193. 


P  =  Adjusting  plug 


FIG.   197. 


FIG.   198, 

views  of  two  designs  of  adjustable  reamers,  and  Fig.  198  is  a  perspective 
view  of  an  expansion-reamer  similar  in  principle  to  Fig.  197.  In  Fig.  196 
the  shank  part  of  the  reamer  is  slotted  to  receive  the  detachable  blades. 
The  ends  of  the  slots  and  one  end  of  the  clamp-nut  are  undercut,  and 
the  ends  of  the  blades  are  correspondingly  angling,  so  that  when  the 
clamp-nut  is  tightened  it  forces  the  blades  inward  against  the  tapering 
plug  P.  To  enlarge  the  reamer  the  clamp-nut  is  slackened  and  the 
plug  P  screwed  inward,  forcing  the  blades  out.  The  nut  is  then  tight- 
ened to  hold  the  blades  firmly  in  place. 


I 


CONSTRUCTION  AND  USE  OF  REAMERS  AND   BITS  137 

In  Fig.  197  the  blades,  instead  of  being  detachable,  are  formed  in- 
tegral with  the  body  of  the  reamer  by  milling  slots  into  the  latter.  These 
blades,  or  cutting  edges,  are  also  forced  outward  by  the  plug  P,  but 
•contract  by  their  own  tension  when  the  plug  P  is  slackened.  Obviously 
the  cutting  edges  in  this  reamer  wj|ll  not  be  forced  out  parallel  as  in  Fig. 
196,  but  will  be  slightly" convex.  However,  as  the  adjustment  is  very 
slight,  and  as  the  reamer  is  generally  passed  clear  through  the  hole, 
the  convexity  of  the  cutting  edges  does  not  seriously  affect  the  accuracy 
of  the  work. 

It  will  be  noticed  that  this  reamer  has  a  fixed  collar  E  on  the  end. 
The  diameter  of  this  collar  is  very  nearly  the  diameter  of  the  hole  to  be 
reamed,  being  .005"  smaller,  and  it  is  designed  to  prevent  careless  work- 
men from  allowing  too  much  for  the  reamer  to  cut.  These  tools  are 
used  mostly  in  hand-reaming,  being  preceded  by  a  machine-reamer 
which  is  within  a  few  thousandths  of  an  inch  of  the  final  size  of  the  hole. 

Chucking-reamers. — The  chucking-reamer  is  so  called  from  the  fact 
that  most  of  the  work  for  which  it  is  used  is  held  in  a  chuck.  It  is  a 
machine-reamer,  and  includes  in  its  class  two  kinds  of  reamers  which 
have  already  been  described,  viz.,  fluted  reamers  and  rose-reamers. 
Fig.  199  shows  a  three-groove  chucking-reamer.  It  is  much  like  the 


FIG.  199. 

twist-drill,  but  cannot  be  used  to  drill  a  hole  from  the  solid.  Its  special 
purpose  is  to  enlarge  cored  holes.  It  is  sometimes  used  in  connection 
with  the  twist-drill  to  prepare  a  hole  for  the  finishing-reamer.  The 
three-groove  chucking-reamer  is  essentially  a  roughing-reamer,  and  it  is 
furnished  with  any  of  the  shanks  mentioned  in  connection  with  twist- 
drills.  It  is  also  made  with  or  without  oil-tubes.  This  reamer  differs 
from  the  three-groove  twist-drill  mainly  in  the  body-clearance,  the 
character  of  which  may  be  understood  from  the  cut. 

Wood  Bits. — The  wood  bit  as  used  in  the  machine-shop  is  made  of 
wood  and  metal.  For  a  size  say  4"  or  smaller  we  use  a  flat  bar  of 
steel  a  little  wider  at  the  cutting  end  than  the  diameter  of  the  required 
hole  and  from  l/4  to  l/2  inch  thick,  as  shown  in  Fig.  200.  On  the 
cutting  end  we  fasten  by  wood-screws  two  pieces  of  wood  from  2  to  4 
inches  long,  which,  with  the  steel,  are  turned  in  the  lathe  to  the  size 


138 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  the  hole.     The  wood  is  then  taken  off  and  the   clearance  filed,  as 
in  a  drill  or  other  tool  of  this  character. 

Far  bits  larger  than  Jf"  we  use,  instead  of  the  flat  bar  of  steel,  a  round 
bar,  to  the  end  of  which  is  secured  a  cast-iron  head  slotted  to  receive 
the  cutters  and  wooden  blocks,  as  in  Fig.  201.  The  cutters  are  held 
in  the  slots  by  set-screws  or  wedges,  and  the  slots  for  the  wooden  blocks, 
being  of  dovetail  shape,  hold  the  blocks  firmly  without  wedges.  The 


G  -  Guide  Blocks  of  Hard  Wood 

B  -  Blade  of  Steel 

C  -Clearance  for  Borings 

FIG.  200. 


H  =  Cutter  Head 
G  =  Guide  Blocks 
C  =  Cutter 


FIG    201. 


cast-iron  head  is  always  made  somewhat  smaller  than  the  hole  to  be 
bored,  leaving  the  cutters  and  blocks  projecting  radially  beyond  the 
periphery  of  the  cast-iron  head.  Having  secured  the  cutters  and  blocks 
in  the  head,  the  whole  is  placed  in  a  lathe  and  turned  to  the  required 
diameter.  The  cutters  are  then  taken  out,  the  clearance  filed,  and  cutters 
tempered  and  replaced,  when  the  bit  is  ready  for  use.  For  small  holes 
these  bits  have  been  largely  superseded  by  forms  of  bits  and  reamer-; 
previously  described,  but  for  very  large  holes  they  are  still  used  to  some 
extent. 

The  object  of  the  wooden  blocks  is  to  help  steady  the  bar  and  to 


CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS  139 

partially  polish  the  hole.  When  the  wooden  blocks  become  worn  they 
are  set  out  by  packing  under  them  with  paper.  It  is  essential,  in  order 
to  get  satisfactory  results,  to  have  the  ivood  fit  tightly  in  the  hole.  The 
objection  to  this  form  of  bit  is>tnat  the  holes  made  with  it  are  not  so 
uniform  in  diameter  as  in  the  casfc  of  the  rose-reamer,  but  the  cost  of  the 
bits  is  less. 

Holders  for  Wood  Bits. — When  made  from  a  flat  bar  of  steel  the 
wood  bit  is  prevented  from  turning  by  a  kind  of  U-shaped  holder  hav- 
ing one  long  and  one  short  limb.  The  long  limb  is  held  in  the  lathe  tool- 
post.  The  larger  sizes  of  bits,  in  which  the  cutters  are  secured  in  a  cast- 
iron  head  keyed  to  a  round  bar,  may  be  held  by  a  lathe-dog;  or  if  the 
shank  ends  be  made  square,  they  may  be  prevented  from  turning  by 
a  common  wrench.  The  wood  bit  is  supported  in  the  lathe  by  the 
work  and  the  tail-stock  center,  the  same  as  a  reamer. 

Tapering-reamers. — For  tapering  holes  it  is  necessary  to  use  some 
form  of  reamer  that  cuts  on  sides  only.  The  rose-reamer,  therefore, 
cannot  be  used  in  tapering  holes.  The  tapering-reamer  may  be  made 
in  the  fluted  form  or  expansion  form,  and  for  rough  work  it  could  be 
made  as  a  half-round  reamer.  Fig.  202  shows  a  fluted  taper-reamer. 


FIG   202. 

When  the  work  is  done  in  the  drill-press,  the  reamer  revolves  and 
the  work  is  stationary.  In  this  case,  if  a  roughing  taper-reamer  is 
not  available,  the  reamer  must  be  preceded  by  several  drills  varying 
in  size  according  to  the  taper  of  the  reamer.  The  smallest  drill  will 
be  smaller  in  diameter  than  the  small  end  of  the  taper,  the  largest  drill 
smaller  than  the  large  end  of  the  taper,  etc.  The  hole,  as  left  by  the 
drills,  will  be  in  steps,  which  steps  are  to  be  cut  out  by  the  reamer. 

When  the  work  is  done  in  the  lathe  the  reamer  is,  with  few  excep- 
tions, stationary  and  the  work  revolves.  The  reamer  is  supported 
on  the  tail-stock  center  and  prevented  from  turning  by  a  drill-holder 
or  lathe-dog.  We  may  use  several  drills  as  in  the  previous  case,  or 
use  one  drill  and  rough  out  the  hole  with  the  boring-tool.  //  the  taper 
attachment  be  used  in  connection  with  the  latter  process,  only  one  taper- 
reamer  will  be  required.  In  many  cases  the  taper  attachment  will  give 
satisfactory  results  without  using  the  reamer  at  all. 


140  MACHINE-SHOP  TOOLS  AND  METHODS 

Roughing  Taper-reamer.  —  A  roughing  taper-reamer  will  do  the 
preparatory  work  much  quicker  than  the  drills.  It  may  be  used  both 
in  the  drill-press  and  in  the  lathe.  Fig.  203  shows  such  a  reamer.  It 


FIG.  203. 

differs  from  the  taper-reamer  in  having  its  cutting  edges  notched. 
These  notches  are  cut  with  a  square-nose  tool  (of  which  the  corners  are 
slightly  rounded)  in  the  form  of  a  left-hand  square  thread.  The  tool 
may  be  I/IQ  to  3/32  inch  wide,  and  the  teeth  may  be  cut  from  l/32  to 
3/32  inch  deep,  according  to  diameter.  The  lead  of  the  thread  is  not 
important. 

Notching  the  cutting  edges  gives  the  reamer  a  very  decided  advan- 
tage. It  relieves  the  broad  bearing,  giving  the  reamer  a  bettei  "bite." 

Considerations  Governing  the  Number  of  Cutting  Edges  in  a 
Reamer. — The  cutting  edges  in  a  reamer  may  be  any  number  from  six 
to  two  dozen,  according  to  size  and  design  of  reamer.  The  last  opera- 
tion on  the  reamer  previous  to  oil-stoning  it  is  to  "back  it  off,"  or  give 
it  body-clearance.  This  is  done  by  a  small  revolving  emery-wheel, 
and  it  is  necessary  that  the  cutting  edges  be  far  enough  apart,  so  that 
when  grinding  one  edge  the  wheel  will  miss  the  other  edge.  For  this 
reason  the  cutting  edges  should  not  be  much  closer  together  than  3/8  of 
an  inch,  except  on  very  small  sizes.  Another  reason  for  keeping  cut- 
ting edges  a  reasonable  distance  apart  is  that  when  too  close  together 
they  clog  up  with  the  borings  and  make  a  rough  hole. 

Shapes  of  Cutting  Edges. — Figs.  204,  205,  and  206  show  cross-sections 
indicating  various  shapes  of  reamer  cutting  edges.  Fig.  205  is  the 
form  most  commonly  used.  In  this  figure  is  indicated  also  the  method 
of  grinding  the  edges.  The  reamer  with  edges  like  Fig.  206  should 
cut  freer  than  any  of  the  others,  but  in  some  cases  the  teeth  seem  to 
spring  outward  and  cut  larger  than  the  nominal  diameter  of  the  reamer. 
This  is  due  to  the  undercut  of  the  teeth  indicated  by  the  dotted  lines. 

Figs.  207  and  208  show  end  views  of  two  of  the  forms  of  reamers 
for  which  the  Brown  &  Sharpe  Manufacturing  Company  furnish  milling- 
cutters.  Accompanying  each  of  these  cuts  is  a  table  giving  the  num- 
bers of  teeth  fpr  the  various  sizes  of  the  reamers  and  the  number  cf 
-the  milling-cutter  to  be  used  in  each  case. 


CONSTRUCTION   AND   USE  OF  REAMERS  AND  BITS  141 


FIG.  205. 


FIG.  206. 


(Number  of 

No.  of 
Cutter. 

Diameter  of  Reamer. 

Teeth  in 
Reamer. 

1 

F'to  \" 

6 

2 

*"  "  r 

6 

3 

II"  "  \" 

6 

,     ( 

r^if  1  1     |// 

6 

4    ] 

ff"  "  \\" 

8 

_    I 

il"  "  ir 

8 

5    1 

\%"  "  if 

10 

6 

,M""2» 

10 

FIG.  207. 


TABLE  FOR  FIG.  207. 


No.  of 
Cutter. 

Diameter  of  Reamer. 

Dumber  of 
Teeth  in 
Reamer. 

1 

I"  to     TS" 

6 

2 

6 

3 

3//    <  <       _7  " 

6 

4 

*"  "    H/r 

6  to  8 

5 

|"    «    1" 

8 

6 

IA"  ;;  ir 

10 

7 

12 

8 

2r  -  3" 

14 

FIG  208 


TABLE  FOR  FIG.  208. 


142 


MACHINE-SHOP  TOOLS  AND  METHODS 


Fig.  207  is  the  same  shape  as  Fig.  205,  the  face  lines  being  radial 
in  both.  The  shape  of  the  teeth  in  Fig.  208  is  such  that  they  cannot 
spring  outward,  but  radial-face  teeth  give  practically  no  trouble  in 
this  respect,  unless  they  are  cut  too  deep. 

Body-clearance  of  the  Reamer.  Causes  of  Chattering. — The  space  A 
between  the  lands  of  the  teeth  and  the  dotted  circle  in  Fig.  209  is  called 


Eccentric  Relief. 
FIG.  209. 

the  body-clearance.  It  should  be  just  sufficient  for  free  cutting.  It 
is  very  important  to  observe  that  excessive  body-clearance  causes  chatter- 
ing, and  a  chattered  hole  is  never  a  smooth  hole.  The  body  clearance 
is  so  little  that  it  is  not  clearly  shown  in  Figs.  204-8. 

The  teeth  of  the  reamer  illustrated  in  Fig.  209  are  made  with  "  eccentric 
relief  or  clearance. "  The  faces  are  radial,  but  the  lands  are  arcs  of  circles 
the  centers  of  these  circular  arcs  being  eccentric  to  the  axial  line  of 
the  reamer.  The  Pratt  &  Whitney  Company,  who  make  these  reamers, 
represent  that  this  form  of  tooth  "is  stronger,"  " reams  a  smoother 
hole,"  and  "does  not  chatter."  In  order  to  clearly  show  the  differ- 
ence between  eccentric  relief  and  flat  relief  a  few  teeth  of  the  latter 
form  are  shown  in  Fig.  210,  the  scale  being  the  same  as  in  Fig.  209.  It 
should  be  noted  that  the  body-clearance  in  both  of  the  figures  is  too 
great.  It  was  purposely  exaggerated  for  the  sake  of  clearness. 

The  body-clearance  in  fluted  reamers  (rose-reamers  are  not  made 
with  this  clearance)  should  not  be  milled  to  the  extreme  edge.  A  sur- 
ace  of  .005  to  .020  inch,  according  to  the  diameter  of  the  reamer, 
should  be  left  concentric  with  the  center.  For  reamers  5/8  to 
l!/4  inches  diameter  an  allowance  of  .010"  will  be  about  right.  The 
clearance  is  usually  brought  to  the  extreme  edge  by  oil-stoning.  The 


CONSTRUCTION  AND  USE  OF  REAMERS  AND  BITS 


143 


stone  should  have  a  true  face,  and  should  never,  for  this  purpose,  be 
used  dry.  Reamers  are  commonly  made  .0005"  large  to  allow  for  wear 
and  stoning.  %  " 

Spacing  the  Cutting  Edges  o^5 Teeth. — It  is  generally  understood  by 
tool-makers  that  a  reamer  with  an  odd  number  of  teeth  will  cut  a  truer 
hole  and  chatter  less  than  one  with  an  even  number.  It  has  been  found, 
however,  that  about  as  good  results  may  be  obtained  by  making  the 
reamer  with  an  even  number  unequally  spaced.  Fig.  204  is  unequally 
spaced  with  this  object  in  view.  From  2  to  4  degrees  will  be  enough 
difference.  It  may  be  well  to  note  that  three  spaces  of  the  27-hole 
circle  will  give  1°  angle  in  spiral  heads  as  ordinarily  geared. 


Fiat  Relief. 
FIG.  210. 

A  fluted  reamer  having  less  than  five  or  six  teeth  is  not  well  adapted 
to  reaming  castings  in  which  there  are  blow-holes.  Six  teeth  or  flutes 
should  be  the  minimum,  and  an  even  number  will  facilitate  measuring 
the  diameter  of  the  reamer.  Spirally  fluted  reamers  give  best  results 
in  reaming  imperfect  castings. 

Miscellaneous  Reamers.  —  Square,  half-round,  and  one-lip  reamers 
are  seldom  used  in  the  machine-shop.  An  exception  to  the  above 
statement  may  be  made  in  favor  of  the  center-reamer,  but  this  will 
receive  attention  in  connection  with  the  subject  of  lathe-centers. 

The  square  reamer  is  sometimes  used  in  brasswork,  and  in  excep- 
tional cases  it  is  used  in  other  work.  It  is  possible  in  an  emergency  to 
make  a  cheap  reamer  by  taking  a  square  bar  of  steel  of  the  required 
dimensions  and  merely  tempering  and  then  grinding  it  on  a  common 
emery-wheel.  If  the  bar  be  slightly  too  large  in  cross-section,  it  may 
be  reduced  by  grinding  two  adjacent  corners  rounding. 


144  MACHINE-SHOP  TOOLS  AND  METHODS 

Hardening  Reamers. — In  the  processes  of  manufacturing,  a  bar  of 
tool-steel  becomes  decarbonized  on  its  outer  surface  by  contact  with  the 
oxygen  of  the  air  while  hot.  This  surface  should  therefore  be  turned 
off  to  a  depth  of  not  less  than  3/64//.  Unless  the  bar  be  centered  fairly 
true,  the  above  requirement  will  necessitate  an  allowance  of  nearly  1/8"~ 
in  diameter  for  machining.  To  lessen  internal  stress  and  the  tendency 
to  curve,  it  is  considered  best  to  turn  a  portion  of  this  metal  off,  and 
then  heat  and  anneal  the  piece  before  taking  the  last  cut.  This  is  done 
whether  the  metal  is  soft  enough  or  not  in  the  rough. 

If  heated  for  hardening  in  a  common  forge,  the  reamer  should  be 
enclosed  in  a  piece  of  gas-pipe.  For  cooling,  use  water  or  brine  (the 
latter  being  preferred)  which  has  been  warmed  just  enough  to  take  off 
the  chill,  and  plunge  the  reamer  (if  of  symmetrical  section)  vertically 
in  the  water.  Holding  the  reamer  over  the  fire  a  moment  or  two  when 
removed  from  the  bath  is  supposed  to  lessen  its  tendency  to  fracture. 

The  temper  of  the  fluted  reamer  may  be  drawn  to  straw-color.  The 
rose-reamer  may  be  somewhat  harder,  or  the  temper  not  drawn  at  all. 
A  hot  tube,  or  other  equivalent,  may  be  used  for  drawing  the  temper, 
the  reamer  being  moved  back  and  forth  in  the  tube  and  rotated  at  the 
same  time. 

Before  grinding  the  reamer  the  centers  should  be  carefully  cleaned 
according  to  instructions  already  given. 


CHAPTER  XI 
LATHES 

Classification  of  Lathes.   Primitive  Form  of  the  Lathe. — Lathes  may 

be  classified  as  hand-lathes,  engine-lathes,  turret-lathes,  and  special 
lathes.  The  turret-lathe  will  be  described  in  a  separate  chapter.  In 
the  great  advancement  of  the  mechanic  arts  during  the  Christian  era 
the  lathe  in  one  form  or  another  has  been  an  indispensable  adjunct. 


FIG.  211. 

It  is  the  oldest  as  well  as  the  most  important  machine-tool  known  to 
the  engineering  profession.  It  would  be  interesting  to  trace  the  lathe 
from  its  first  conception  to  its  present  state  of  perfection,  but  the  space 
available  will  not  permit  a  thorough  consideration  of  this  matter.  We 
have,  however,  prepared  a  sketch  (Fig.  211)  of  the  most  primitive  form 

145 


146 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  lathe,  that  the  reader  may  be  able  to  observe  the  contrast  between  it 
and  the  modern  type.  Referring  to  the  sketch,  A  and  A  1  are  two  posts 
answering  respectively  to  the  head-stock  and  tail-stock  of  our  present 
lathe,  B  and  B  1  the  centers  and  G  the  rest  or  support  for  the  cutting- 
tool.  The  treadle  E  is  operated  by  foot-power  as  in  a  common  sewing- 
machine.  D  is  a  rope  extending  from  the  treadle  to  the  sapling  above, 
and  wrapped  one  revolution  around  F;  F  is  the  work  to  be  turned. 
This  lathe  was  first  used  for  wood-turning,  and  the  piece  F  was  made 
approximately  round  before  it  was  placed  between  the  centers.  The 
action  of  the  foot  on  the  treadle  imparted  an  oscillating  motion  to  the 
work,  and  the  cutting-tool  was  pressed  against  the  work  during  the 
downward  movement  of  the  treadle.  During  the  upward  stroke  the 
tool  was  withdrawn,  allowing  the  sapling  to  reverse  the  motion  of  the 
work.  Obviously  the  first  improvement  likely  to  be  suggested  in  con- 
nection with  this  lathe  would  be  the  substitution  of  a  wooden  frame 


FIG.  212. 

for  the  two  posts,  and  this  was  done.  Also,  a  beam  of  suitable  shape 
and  material  took  the  place  of  the  sapling.  Lathes  continued  to  be  used 
in  a  more  or  less  crude  form  for  centuries,  the  cutting-tool  being  held 
by  hand  and  supported  on  a  rest  substantially  as  in  our  present  wood- 
lathe. 

The  Slide-rest.  Hand-lathes. — One  of  the  most  important  of  later 
improvements  is  the  slide-rest  shown  in  Fig.  212.  In  this  device  the 
cutting-tool,  instead  of  being  held  by  hand,  is  rigidly  secured  by  a  set- 


LATHES 


147 


screw,  and  accurately  guided  by  planed  ways.    This  rest  is  designed 
for  a  hand-lathe  and  is  not  self-acting. 

The  hand-lathe  is  shown  intF!g.  213,  and  it  is  substantially  the  same 
as  a  common  wood-lathe.  In  th^  illustration  B  is  the  bed,  H  the  head- 
stock,  R  the  rest,  P  the""cone  pulley,  and  C  the  counter-shaft.  On  most 
hand-lathes  the  tool-rest  used  is  similar  to  that  used  in  wood-turning, 
and  the  tool  is  held  by  hand  in  the  same  manner  as  in  wood- turning. 


FIG.  213. 

But  in  some  of  the  better  classes  of  hand-lathes  the  slide-rest  mentioned 
above  is  used. 

The  Engine-lathe. — In  the  modern  type  of  lathe,  known  as  the  engine- 
lathe,  the  tool  is  traversed  automatically  parallel  with,  and  at  right 
angles  to  the  axis  of  the  lathe-spindle.  Such  a  lathe  is  also  furnished 
with  a  system  of  change-gears  by  which  the  ratio  of  tool  traverse  to 
spindle  revolution  may  be  changed  to  cut  different  leads  of  screws. 
Fig.  214  shows  a  good  example  of  this  lathe. 

Referring  to  the  figure,  B  is  the  bed,  supported  on  legs  as  shown.  H 
is  the  head-stock,  carrying  the  main  spindle  on  which  run  the  cone  pulley 
P  and  its  pinion  G  9,  and  to  which  are  keyed  G  3  and  G  8.  T  is  the  tail- 


148 


MACHINE-SHOP  TOOLS  AND  METHODS 


stock,  made  adjustable  lengthwise  of  the  lathe,  and  having  a  spindle  also 
adjustable  by  means  of  the  hand- wheel  HI.    R  is  the  slide-rest,  movable 


on  C  at  right  angles  to  the  main  spindle.  Swiveling  on  R  is  the  compound 
rest  R  1,  carrying  the  tool-post  T  1,  in  which  is  secured,  by  a  set-screw, 
the  tool.  -R  1  is  operative  at  any  angle  in  a  horizontal  plane. 


LATHES  149 

The  apron  A  is  bolted  to  the  carriage  C.  Secured  to  the  inner  side 
of  the  apron  is  a  system  of  gearing  which,  in  connection  with  the  gearing 
G  I  and  pulleys  F  1,  gives  automatic  movement  to  the  carriage. 

The  Screw-cutting  Mechanism.— When  cutting  threads  (making  the 
helical  grooves  of  a  screw)  a  4»ery  exact  movement  of  the  carriage  is 
required,  and  for  this  purpose  the  lead-screw  *  S,  operated  by  the  gearing 
G  1 ,  is  used.  This  gearing  is  driven  by  means  of  the  gear  G  3  on  main 
spindle,  which  connects  with  gearing  on  the  short  shaft  passing  through 
upper  pulley  F  1.  The  screw  S  revolves  in  a  threaded  box  secured  to 
the  apron  A.  This  box  is  made  in  halves,  which,  by  means  of  a  handle 
on  the  outside  of  the  apron,  may  be  closed  upon  or  released  from  the 
screw.  The  train  of  gearing  G  1  may,  by  means  of  the  lever  L,  be  engaged 
with  or  disengaged  from  the  gear  G  3  and  also  reversed.  When  engaged, 
and  the  screw  S  is  revolving,  the  closing  of  the  threaded  box  upon  the 
screw  causes  the  carriage  C  with  apron  A  to  traverse  the  lathe-bed  at  a 
ratio  depending  upon  the  lead  of  the  required  screw  and  the  change- 
gears  at  G  1 .  When  the  box  is  open  the  screw  has  no  effect  on  the  carriage. 

The  Feed  Mechanism. — In  order  to  preserve  the  accuracy  of  screw  S 
for  screw-cutting  the  feed-rod  F  is  used  for  feeding.  This  rod  is  operated 
by  a  belt  connecting  the  pulleys  F  I.  On  this  rod,  on  the  inner  side  of 
the  apron,  is  a  worm  which  is  turned  by  the  rod  by  means  of  a  feather- 
key.  This  key  fits  the  worm  with  sufficient  freedom  to  permit  the  worm 
to  slide  upon  the  rod.  The  worm  operates  a  train  of  gears,  the  first  of 
which  is  a  worm-gear,  and  the  last  a  pinion  (small  gear)  working  in  a  rack 
R  4.  The  latter  is  bolted  to  the  lathe-bed,  and  when  the  pinion  turns 
it  causes  the  lathe-carriage  to  traverse  the  bed  parallel  with  the  main 
spindle.  By  another  system  of  mechanism,  also  operated  by  the  feed- 
rod,  the  rest  R  is  caused  to  traverse  the  carriage  C  at  right  angles  to 
the  main  spindle.  These  movements  may  be  started  or  stopped  by 
handles  on  the  outside  of  the  apron.  They  may  also  be  effected  by  hand 
by  means  of  the  handles  H  2  and  H  3. 

Using  the  Screw  as  a  Feed-rod. — In  some  lathes  the  screw  is  used 
for  both  screw-cutting  and  feeding,  dispensing  with  pulley  F 1  and 
feed-rod  F.  Fig.  215  shows  the  apron  and  accompanying  mechanism 
for  such  a  lathe.  The  threaded  boxes  B  I  are  opened  and  closed  upon 
the  screw  S  as  before  for  screw-cutting;  but  for  the  ordinary  feed  the 
thread  upon  the  screw  is  not  used.  For  this  purpose  the  screw  is  used  as 
a  feed-rod.  The  worm  W  revolves  with  the  screw,  and,  engaging  with 

*  The  long  screw  which  moves  the  lathe  for  thread-cutting  is  commonly  called 
the  lead-screw. 


LATHES 


151 


the  worm-wheel  W  1,  causes  the  latter  to  turn.  Secured  to  the  same 
shaft  with  W  1  is  a  small  gear  G  7,  shown  in  Fig.  216,  which  engages 
with  G  4.  Cast  integral  with  G  4  is  G  5,  which  meshes  with  the  rack 
R  4  fixed  to  the  bed  as  in  the  previous  case. 


FIG.  216. 

Fig.  215  shows  only  the  mechanism  for  traversing  the  carriage. 
Fig.  217  is  more  complicated  and  shows  both  the  carriage-feed,  and  the 
cross-feed  mechanism  for  rest  R.  The  latter  is  effected  by  gear  G  6 
meshing  with  a  small  gear  on  cross-feed  screw. 

Reverse  Gears  under  Head-stock. — In  the  system  just  described,  which 
is  quite  different  from  that  shown  in  Fig.  214,  the  carriage  is  in  some 
lathes  reversed  by  miter-gears  under  the  head-stock.  The  mechanism 
for  this  purpose  is  shown  in  Figs.  218  and  219,  and  the  lathe  of  which 
it  is  a  part  is  shown  in  Fig.  220.  In  Figs.  218  and  219  a,  b,  c,  and  d  are 
part  of  a  train  of  gears  for  operating  the  lead-screw ;  c  is  not  connected 
directly  to  the  shaft  S  3,  but  is  secured  to  the  hub  of  the  miter  gear  g, 


LATHES 


153 


od 


LATHES 


155 


156  MACHINE-SHOP  TOOLS  AND  METHODS 

through  which  shaft  S  3  passes,  g  being  journaled  in  the  head-stock  as 
shown.  This  gear  meshes  with  the  miter  h,  which  in  turn  drives  i. 
Between  the  gears  g  and  i,  and  driven  by  a  feather-key  in  shaft  S  3,  is 
clutch  y.  This  clutch  has  two  projecting  lugs  (one  at  each  end),  and  the 
gears  g  and  i  have  similar  lugs,  which  are  designed  to  engage  the  lugs  on 
y.  The  clutch  may  be  held  in  a  neutral  position,  or  may  be  engaged 
with  either  g  or  i  by  means  of  the  levers  k  and  I,  which  are  connected 
to  a  lever  on  the  lathe-apron  by  means  of  the  rod  m.  The  gears  g,  h,  i 
are  running  whenever  c  is,  and  if  the  clutch  be  moved  to  engage  with 
g,  it  (the  clutch)  will  revolve  with  g ;  if  it  engage  with  i,  it  will  revolve 
with  i,  which,  from  the  nature  of  the  connection,  is  in  an  opposite  direc- 
tion to  that  of  g. 

As  the  clutch  j  is  secured  by  a  feather-key  to  the  shaft  S  3,  the  latter 
must  turn  when  the  clutch  turns  and,  with  the  foregoing  description, 
there  should  be  no  difficulty  in  understanding  how  to  obtain  two  opposite 
motions  of  shaft  S  3.  The  clutch  and  miter-gear  mechanism  above 
referred  to  is  more  clearly  shown  in  Fig.  221. 

An  Improved  Gearing  System.— It  remains  to  show  the  mechanism 
connecting  shaft  S  3  with  the  apron-gearing.  Figs.  218,  219,  220,  and  222 
show  one  of  the  modern  gearing  systems  for  this  purpose.  In  using 
lathes  of  the  old  type  it  is  necessary  to  take  off  and  put  on  change-gears 
for  each  particular  lead  of  thread  to  be  cut.  But  in  the  lathe  under  con- 
sideration thirty-six  different  leads  may  be  cut  without  detaching  any 
gears.  The  construction  provides  also  for  the  use  of  change-gears.  This 
last  provision  makes  it  possible  to  cut,  in  addition  to  the  thirty-six 
threads,  many  other  leads,  the  range  being  limited  only  by  the  number 
of  extra  change-gears  supplied. 

It  may  be  well  to  give  a  detailed  description  of  this  system.  On  the 
lead-screw  S,  Figs.  219, 220,  and  222,  we  have  a  "cone  of  gears"  which  are 
marked  1  to  12  in  Fig.  22g)  On  shaft  o  of  the  last-mentioned  figure  is 
the  gear  13,  which  with  its  intermediate,  14,  may  be  moved  along  and 
-  rotated  through  a  short  arc  on  the  shaft  by  the  lever  n  (Fig.  218).  By 
this  means  gears  13  and  14  may  be  brought  into  engagement  with  either 
of  the  gears  marked  1  to  12,  and  when  in  position  they  may  be  locked 
by  the  spring  lock  p  (Fig.  218)  which  engages  with  any  of  the  holes  shown 
under  the  cone  of  gears  in  Fig.  219.  Fig.  222;  shows  gears  13  and  14  in 
position  to  drive  gear  7.  If  now  these  gears  be  set  in  motion  (the  ratio 
up  to  this  point  being  assumed  1  to  1),  the  lead-screw  S  (Figs.  219  and 
220)  will  revolve  at  a  ratio  with  the  lathe-spindle,  depending  upon  the 
ratio  of  the  diameter  of  gear  13  to  gear  7.  And  similarly,  if  the  two 


158  MACHINE-SHOP  TOOLS  AND  METHODS 

sliding  gears  be  caused  to  engage  with  any  other  one  of  the  gears  1  to 
12,  the  ratio  will  be  changed,  its  value  being  shown  on  an  index  plate 
secured  to  the  lathe. 

In  the  gear-box  B  3  (Figs.  218  and  219)  is  a  second  nest  of  gears, 
which  are  controlled  by  the  lever  n  1.  These  give  three  changes,  the 
three  positions  of  the  lever  being  indicated  by  the  numbers  1,  2,  and  3 
on  the  gear-box.  The  gears  in  gear-box  B  3  drive  those  in  B  2  and  the 
combination  of  the  two  sets  of  gears  provide  for  the  thirty-six  changes; 
that  is  to  say,  that  for  each  position  of  the  lever  n  1  twelve  different 
threads  are  cut. 

Connection  is  made  between  the  gears  in  box  B  3  and  the  "stud  gear" 
d  (Fig.  219)  by  two  gears,  e  and  /.  These  are  keyed  to  a  quill  shaft 
which  runs  freely  on  a  stud  secured  to  the  sector  S  4  (see  Fig.  218). 
The  gear  /,  which  is  on  the  outer  end  of  the  quill,  is  one  of  the  change- 
gears  referred  to  above,  and  the  sector  is  slotted  and  locked  at  L  1  in  the 
usual  manner  to  admit  of  the  use  of  various  sizes  of  change-gears. 

Quite  a  number  of  speed-changing  devices  have  been  introduced 
during  the  past  15  years,  but  they  do  not  differ  greatly  from  the  one  just 
described.  Some  of  these  devices  are  shown  in  connection  with  other 
machines  in  this  work,  and  most  of  them  have  been  illustrated  in  "  The 
American  Machinist,"  in  "  Machinery,"  and  other  technical  journals. 

The  Feed-clutches. — In  the  mechanism  just  described  the  feed,  as 
previously  stated,  is  effected  by  the  lead-screw  which  is,  for  this  pur- 
pose, operated  by  gearing  as  a  feed-rod,  just  as  though  there  was  no  thread 
on  it.  The  means  of  disengaging  the  feed  is  shown  in  Fig.  216.  Re- 
ferring to  this  figure,  W  1  is  the  worm-gear  shown  in  Fig.  215,  and  F  2 
is  the  friction-clutch  driven  with  the  shaft  S  1  by  means  of  the  feather- 
key.  Near  middle  of  shaft  S  1  is  tightly  keyed  the  small  gear  G  7, 
which  gear  is  hid  behind  W  1  in  Fig.  215.  By  means  of  the  small 
threaded  shaft  S  2,  which  passes  through  S  1,  and  its  knob  K,  the  clutch 
F2  may  be  caused  to  engage  with  the  beveled  bearing  of  W  1.  If 
now  screw  S  revolve,  the  train  of  gearing  will  cause  the  carriage  to 
traverse  the  lathe-bed.  When  the  clutch  F2  is  released,  the  worm- 
gear  turns  loosely  on  shaft  S  1  and  has  no  effect  on  the  other  gears. 

As  has  been  stated,  this  system  requires  neither  feed-belt  nor  feed- 
rod. 

Bevel-gear  Reverse  in  Apron. — The  apron  mechanism  in  Fig.  223 
differs  but  little  from  the  common  form.  It  is  similar,  however,  to  that 
last  described  with  respect  to  the  lead-screw,  which  is  used  for  both 
screw-cutting  and  feeding.  The  lead-screw  passes  through  the  bevel- 


LATHES 


161 


20/6o  or  x/3  revolution,  and  G  10  will  make  the  same.  Suppose,  again, 
G  10  has  20  teeth  and  G  8  60  teeth;  now  when  G  10  makes  1/3  revolution 
G  8  will  make  1/3><20/60=1/9-  I*  other  words,  the  ratio  of  revolutions 

*  j 

of    53    to    P=^rX^7-3-  =  20/6o^2%o=1/9.      With    a    four-step    cone 


we  should  have  four  speeds  in  gear  and  four  out  of  gear,  making  eight 
speeds  in  all,  and  these  speeds  should  be  in  geometrical  progression. 


FIG.  225. 

Spur-gear  Reversing-mechanism.  —  In  connection  with  Fig.  214, 
it  was  stated  that  the  train  of  gears  G  1  could  be  disengaged  from  the 
gear  G  3  on  the  main  spindle,  or  reversed.  The  means  of  effecting  these 
changes  will  now  be  explained.  Referring  to  Fig.  225,  the  three  gears 
marked  G  1  are  the  same  train  of  gears  that  are  designated  G  1  in  Fig. 
214.  The  uppermost  of  these  three  gears  is  on  the  short  shaft  which 
carries  one  of  the  feed-cones,  and  which  passes  through  the  head-stock. 
Inside  the  head-stock  and  on  this  same  shaft  is  a  gear  G  13  (Fig.  224), 
which  G  12  engages.  Meshing  with  G  12  is  G  11,  and  G  12  and 


162 


MACHINE-SHOP  TOOLS  AND  METHODS 


Gil  may  be  rotated  through  a  short  arc  on  the  axis  of  the  upper  gear  G 1 
by  the  lever  L,  both  of  these  gears  being  supported  on  a  swinging  bracket. 
When  lever  L  is  raised  it  brings  G  12  into  mesh  with  G  3  (Fig.  224), 
and  the  train  of  gears  G  I  are  driven  in  a  forward  direction.  When 
lever  L  is  depressed  G  12  is  disengaged  from  G  3,  and  G  11  is  brought  into 
mesh  with  the  latter.  We  now  have  four  gears  in  mesh,  not  including 
those  on  the  outside  of  the  headstock.  This  is  a  very  common  method 


> 


FIG.  226. 

of  getting  two  opposite  motions  by  spur-gears.  It  should  be  noted  that 
Gil  runs  idly  when  G  12  is  in  mesh  with  G  3,  but  that  G  12  drives  Gil 
when  the  latter  is  in  mesh  with  G  3.  By  placing  the  lever  in  an  inter- 
mediate or  neutral  position,  both  G  11  and  G  12  are  disengaged  from 
G  3,  and  the  train  of  gearing  becomes  inoperative.  The  middle  gear 
G  1,  which  is  known  as  the  "intermediate"  gear,  turns  freely  on  a  stud 
held  in  a  slotted  sector  as  shown.  The  sector  itself  is  also  held  to  the 
head-stock  by  one  bolt  passing  through  the  slotted  projection.  The 
object  of  this  arrangement  is  to  provide  the  adjustment  necessary  in 
using  different  sizes  of  "change"  gears.  The  student  should  observe 
the  difference  between  this  method  of  getting  two  opposite  motions 
and  that  referred  to  in  connection  with  Fig.  219. 


•*&  " 


> 


LATHES 


163 


Triple-gear  Lathe. — It  should  be  understood  that  the  object  of  the 
back  gearing  in  a  lathe  is  to  give  a  higher  velocity  ratio  between  the 
belt  and  the  lathe-spindle.  On  the  larger  lathes  this  velocity  ratio 
is  still  further  increased  by  the  addition  of  another  shaft  carrying  two 
additional  gears.  Fig.  226  shows&a  rear  side  view  of  a  lathe  head-stock 
with  triple  gears.  The  triple-gear  shaft  is  seen  directly  under  the  regu- 
lar back-gear  shaft,  and  it  is  driven  by  a  gear  on  the  latter.  This  triple- 
gear  shaft  drives  the  main  spindle  of  the  lathe  by  means  of  a  pinion 


FIG.  227. 

which  engages  with  the  annular  gear  shown  on  the  back  side  of  the 
lathe  face-plate. 

Geared-head  Lathes. — In  the  chapter  on  Drilling-machines  allusion 
was  made  to  the  tendency  to  substitute  tooth-gearing  for  the  main 
cone  pulleys  in  machine-tools.  Fig.  227  shows  the  new  head-stock  of 
the  Lodge  and  Shipley  lathe,  embodying  this  principle.  Instead  of 
the  cone  pulley  there  is  one  wide-faced  pulley.  This  pulley  has  no  bear- 
ing on  the  main  spindle,  but  is  secured  to  a  hollow  shaft  which  is  jour- 
naled  in  the  two  bearings  shown.  At  the  left  side  of  the  pulley  and 
keyed  to  the  same  hollow  shaft  are  two  gears  G  and  G  1  of  different 


164 


MACHINE-SHOP  TOOLS  AND  METHODS 


sizes.  The  main  spindle  of  the  lathe  passes  through  the  hollow  shaft 
mentioned,  but  does  not  touch  it,  being  journaled  in  the  two  outer 
bearings.  Near  the  left  end  of  the  back-gear  shaft  are  two  sliding 
gears,  either  of  which  may  be  engaged  with  its  mating  gear  on  the  hol- 
low shaft  to  which  the  pulley  is  secured.  When  not  in  use  these  slid- 
ing gears  are  located  between  the  two  gears  of  the  pulley-shaft.  The 
two  pairs  of  gears,  in  connection  with  the  pinion  on  the  right  end  of 
the  back-gear  shaft  and  its  mating  gear  G  2  on  the  spindle,  give  two 
speeds  to  the  spindle.  The  back-gear  shaft  is  thrown  out  of  mesh  by 
the  usual  eccentric  arrangement,  and  when  thus  disengaged  the  pulley- 
shaft  may  be  locked  by  a  clutch  to  the  main  spindle,  the  clutch  being 
operated  by  the  lever  L.  This  direct  connection  gives  another  speed, 
making  three  speeds  in  all.  There  are  three  different  speeds  on  the 
counter-shaft,  and  thus  the  lathe  is  provided  with  nine  speeds. 

In  Fig.  228  the  main  spindle  with  its  gear  G  2  is  shown  removed 
from    the   bearings,   exposing   the    clutch-teeth    on   the    pulley-shaft. 


FIG.  228. 

Being  relieved  of  the  belt-pressure,  the  durability  and  accuracy  of  the 
spindle-bearings  in  this  lathe  are  considerably  increased. 

Fig.  229  shows  a  lathe  designed  with  special   reference  to  the  re- 


LATHES  165 

quirements  of  the  "high-speed"  steel.      In  this  lathe  the  geared  head  is 
not  employed,  but  a  cone  pulley  with  three  wide  steps  of  large  diameter 


FIG.  229. 

is  used.  This  lathe  is  referred  to  in  the  catalog  as  the  "American 
High-speed  Lathe."  The  manufacturers  of  this  lathe  make  also  a 
"geared-head  lathe." 

Raise-and-f all  Rest.  —  The  ordinary  slide-rest  of  the  engine-lathe 
is  so  constructed  that  the  cross-feed  slide  cannot  be  raised.  The  means 
for  adjusting  the  tool  vertically  requires  that  the  set-screw  holding 
the  tool  be  slackened.  When  the  set-screw  is  slackened  the  point  of 
the  tool  may  be  raised  or  lowered  by  slightly  rotating  a  convex  gib 
in  a  concave  washer.  Fig.  230  shows  a  rest  which  has  the  last-named 
method  of  adjusting  the  tool,  which  method  is  clearly  indicated  in  the 
cut,  and  in  addition  thereto  it  has  a  means  of  adjusting  the  tool  by 
raising  the  rest  itself.  When  adjusted  the  rest  may  be  bolted  firmly 
in  position  in  connection  with  the  bolt  and  slot  shown.  Just  above 
this  bolt  is  also  seen  a  handle  for  raising  the  rest. 

The  raise-and-fall  rest  is  preferred  by  some  mechanics  for  the  smaller 
lathes,  but  it  is  not  well  adapted  to  the  heavier  lathes. 

The  Plain  Rest. — The  plain  rest  shown  in  Fig.  231  differs  from  the 
rest  on  the  lathe  in  Fig.  214,  in  that  it  lacks  the  upper  slide  of  the  com- 
pound rest.  Its  cross-slide,  therefore,  cannot  be  fed  in  any  other  direc- 
tion than  at  right  angles  to  the  lathe  axis.  This  is  a  disadvantage 
on  many  kinds  of  work,  but  the  extra  rigidity  possible  in  this  kind  of 
rest  compensates  in  part  for  the  lack  of  the  angular  feed. 

The  Compound  Rest. — The  compound  rest  which  has  been  referred 
to  in  connection  with  Fig.  214  is  shown  in  detail  mounted  upon  the 
lower  slide-rest  in  Fig.  232.  Properly  speaking  the  combination  of 


1C6  MACHINE-SHOP  TOOLS  AND  METHODS 

R  and  R  1  constitute  the  compound  rest,  but  the  term  is  often  used 


FIG.  230 

to  refer  to  R  1,  which  swivels  on  R.     The  graduations  for  setting  the 
rest  for  angular  feed,  and  one  of  the  bolts  for  clamping  it,  are  clearly 


FIG.  231. 


shown  in  the  cut.     Many  manufacturers  so  design  the  lathe-carriage 
that  either  the  plain  rest  or  the  compound  rest  may  be  used. 


LATHES 


167 


The  Elevating  Tool-rest. — There  have  been  invented  a  great  many 
different  tool-rests  with  the  object  of  overcoming  the  difficulty  referred 


FIG.  232. 

to  in  connection  with  the  ordinary  slide-rest.  Fig.  233  shows  one  of 
these  designs.  The  rest  is  raised  by  the  screw  seen  projecting  just  above 
the  tool. 


FIG.  233. 


The  Open-side  Tool-rest. — In  the  ordinary  tool-post  the  lathe-tool 
is  held  by  one  set-screw.  It  may  be  more  rigidly  held,  however,  by 
two  set-screws,  as  shown  in  the  tool-post  in  Fig.  234.  The  third  set- 
screw  shown  is  used  for  clamping  the  upper  part  of  the  block  to  the 
next  lower  part.  By  slacking  this  third  set-screw  the  tool  may  be 
swung  around  to  any  angle  and  then  clamped. 


168 


MACHINE-SHOP  TOOLS  AND   METHODS 


Three-tool  Shafting-rest. — This  device  is  shown  in  Fig.  235.     As 
indicated  by  its  name,  this  rest  is  designed  more  particularly  for  turn- 


FIG.  234. 


ing  long  shafting.     For  this  purpose  two  of  the  tools  may  be  used  for 
roughing  cuts  and  the  third  tool  for  smoothing  cuts,  the  shaft  being 


FIG.  235. 

finished  at  one  traverse  of  the  lathe-carriage.  While  being  turned, 
the  shaft  is  kept  cool  with  water  supplied  from  the  tank  shown.  The 
ring-shaped  casting  shown  under  the  tank  is  a  kind  of  follower-rest 
which  travels  with  the  carriage,  and  supports  the  shaft  against  the 
pressure  of  the  tools.  It  is  designed  to  receive  bushings  for  different 


LATHES 


169 


sizes  of  shafts,  which  bushings  are  held  by  a  set-screw  on  the  top  of 
the  casting.     As  indicated  in  the  cut,  this  attachment  is  held  to  the 


lathe-carriage  by  four  bolts,  and  it  may  be  removed  and  replaced  by 
the  ordinary  cross-slide. 


170 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  three-tool  shafting-rest  is  one  of  the  distinguishing  features  of 
a  special  shafting-lathe.  Such  a  lathe  is  usually  provided  also  with  a 
screw-press  for  straightening  shafts.  In  other  respects  the  shafting- 
lathe  is  not  sufficiently  different  from  the  common  lathe  to  justify  a 
full  description  here. 

The  Taper  Attachment. — The  taper  attachment  shown  in  Fig.  236 
is  a  device  used  for  causing  the  tool  to  move  to  or  from  the  work  while 
the  lathe-carriage  moves  longitudinally,  the  object  being  to  turn  tapers. 
This  attachment  is  more  particularly  described  in  the  chapter  on  Lathe 
Work,  as  are  also  the  steady-rest  and  follower-rest. 


FIG.  237. 

The  Pulley-lathe. — The  lathe  shown  in  Fig.  237  is  designed  especially 
for  turning  pulleys.  This  machine  is  provided  with  two  tool-rests  so 
that  a  roughing  and  a  finishing  cut,  or  two  roughing  cuts,  may  be  taken 
simultaneously.  As  the  two  rests  are  on  opposite  sides  of  the  lathe, 
one  of  the  tools  must  be  inverted.  The  arm  shown  at  the  left  end  of 
the  lathe  is  a  kind  of  tail-stock  which  may  be  swung  around  on  its  axis 
to  admit  of  more  convenient  removal  of  the  pulley.  The  latter  while 


LATHES 


171 


being  turned  is  held  on  an  arbor  one  end  of  which  is  supported  by  the 
tail-stock,  the  other  end  being  fitted  to  the  hollow  spindle  of  the  lathe. 
This  makes  the  arbor  more  rigid»  than  if  held  at  both  ends  on  centers. 
The  pulley  is  rotated  by  two  drive|s  seen  bolted  to  the  face-plate  of  the 
machine,  which  drivers  engage  with  two  of  the  arms  of  the  pulley.  To 
facilitate  crowning  the  pulley,  the  rails  supporting  the  two  rests  are 
mounted  upon  a  substantial  bed-plate  which  may  be  swung  upon  a  pivot 
and  clamped  at  the  required  angle. 

The  Pit-lathe  (Fig.  238). — This  is  a  very  heavy  and  powerfully  geared 
lathe.    It  is  designed  for  machining  fly-wheels  and  other  heavy  work  of 


FIG.  238. 

which  the  diameter  is  large  and  the  length  inconsiderable.  Work  of  this 
character  is  always  bolted  to  the  large  face-plate,  which  swings  in  the 
pit  as  shown.  The  head-stock  and  other  framework  of  the  lathe  are 
supported  upon  a  foundation  of  heavy  masonry.  This  machine  has 
two  tool-rests.  One  of  these  has  a  movement  parallel  to  the  face-plate, 
the  movement  of  the  other  being  at  right  angles  to  the  face-plate.  Each 
of  these  rests  has  also  another  shorter  movement. 


172  MACHINE-SHOP  TOOLS  AND  METHODS 

A  Lathe  for  Turning  Driving-wheels. — In  railway  machine-shops 
and  in  shops  which  build  locomotives  a  special  lathe  is  used  for  turning 
locomotive  driving-wheels.  This  lathe  has  two  face-plates,  two  spindles, 
and  two  tool-rests.  It  is  in  reality  two  lathes  on  one  bed,  the  object 
being  to  turn  the  two  wheels  of  the  locomotive  driving-shaft  simultane- 
ously. These  lathes  are  generally  so  designed  that  either  of  the  face- 
plates may  be  operated  independently.  When  so  designed  the  lathes 
may  be  used  for  boring,  the  work  being  bolted  to  the  face-plate. 

The  Gap -lathe.  Increasing  the  Swing  of  a  Lathe. — The  gap-lathe 
is  a  lathe  having  a  kind  of  gap  made  in  the  bed  near  the  head-stock; 
in  other  respects  it  is  similar  to  the  common  engine-lathe.  The  object 
of  the  gap  is  to  admit  of  boring  large  pulleys,  etc.,  in  a  small  lathe.  This 
expedient  is  adopted  to  a  greater  extent  in  England  than  in  America. 

A  lathe  has  recently  been  designed  in  the  United  States  with  auxiliary 
head  and  tail  spindles,  the  object  being  in  the  main  similar  to  that  of 
the  gap-lathe.  These  auxiliary  spindles  are  raised  above  the  regular 
spindles. 

The  common  method  of  increasing  the  swing  of  a  lathe  is  to  use 
cast-iron  blocks  under  the  head-stock  and  tail-stock  and  extend  the 
tool-post. 

The  Tool-room  Lathe. — This  is  a  small  engine-lathe  made  with  special 
accuracy,  and  with  draw-in  collets  and  some  other  attachments  not 
usually  found  on  the  ordinary  lathe. 

Cutting  Speeds  for  the  Engine-lathe. — There  are  so  many  considera- 
tions entering  into  the  problem  that  it  is  difficult  to  give  a  specific  rule 
for  the  speed  at  which  a  lathe  should  run  for  any  given  diameter  of 
work.  It  should  run  faster  for  soft  material  than  for  hard,  and 
generally  faster  for  light  cutting  than  for  heavy  cutting.  One  authority 
gives  20  feet  per  minute  as  an  average  cutting  speed  for  cast  iron  and 
steel,  but  the  tendency  is  toward  much  faster  speeds.  For  roughing  cuts 
on  wrought  iron  and  soft  steel  the  speed  may  be  from  30  to  45  feet  per 
minute.  Cast  iron  may  usually  be  cut  at  somewhat  higher  speed.  The 
speed  for  brass  may  be  from  80  to  100  feet,  and  extra-soft  brass  may 
sometimes  be  cut  at  a  speed  of  more  than  100  feet  per  minute.  When 
the  tool  becomes  excessively  hot  and  wears  away  too  rapidly,  it  is  an 
indication  that  the  speed  is  too  high.  When  it  cuts  freely  and  remains 
cool  the  speed  may  usually  be  increased.  In  cutting  very  hard  material, 
such  as  chilled  iron,  for  instance,  it  is  sometimes  necessary  to  run  as  slowly 
as  8  to  10  feet  per  minute. 

The  cutting  speed  is  always  taken  on  the  circumference,  and  in  feet 


LATHES  173 

per  minute.     Thus,  to  turn  a  3"  steel  shaft  at  a  cutting  speed  of  30 

12  X30 

feet  per  minute  would  require  5  —  5~jTTA  =  38.22  revolutions  of  the  lathe- 

o  X  oj. 


spindle  per  minute.  The  lathe  seldom  has  the  exact  speed  required,  so 
that  we  take  the  nearest  -speed. 

High-speed  Steel.  —  The  above  assumes  the  use  of  ordinary  steel  tools, 
but  the  new  steel  previously  mentioned  will  stand  a  very  much  greater 
speed  and  heavier  cutting,  and  it  will  doubtless  largely  supersede  the 
older  steel  in  the  near  future.  Among  the  brands  now  on  the  market 
are  "Novo,"  "Blue  Chip/'  and  "Capitol."  The  makers  of  some  of 
these  brands  of  steels  guarantee  them  to  stand  a  cutting  speed  of  150 
to  200  feet  per  minute.  The  heat  generated  by  such  speed  does  not 
injure  the  high-speed  steels  as  it  does  the  ordinary  steels.  In  estimating 
the  saving  due  to  the  use  of  the  high-speed  steel  it  should  be  borne  in 
mind  that  doubling  the  cutting  speed  does  not  double  the  product  of 
the  lathe.  The  reason  for  this  is  that  a  considerable  percentage  of  the 
time  is  consumed  in  adjusting  the  work  in  the  lathe,  grinding  tools,  etc. 
It  should  be  the  object,  however,  of  the  intelligent  foreman  to  adopt 
such  methods  as  shall  reduce  this  "dead  time"  to  a  minimum. 

Feeds.  The  Rotary  Measure.  —  There  is  as  much  difficulty  in  giving 
a  rule  for  the  rate  of  feeding  as  for  the  cutting  speed.  The  feed  may 
vary  between  Y^s"  per  revolution  and  1"  per  .revolution.  About 
Yso"  per  revolution  would  be  right  in  most  cases  for  roughing  cuts  on 
steel  shafts  of  moderate  diameters,  and  about  Ys2"  for  cast  iron.  Ma- 
chinists generally  use  very  fine  feeds  for  finishing  cuts  on  small  steel 
shafts  —  say  Yi25  to  Yioo  inch  per  revolution.  Both  the  roughing  and 
finishing  cuts  may  be  somewhat  faster  in  heavier  work.  On  large  cast- 
iron  work,  where  the  fine  finish  is  not  required,  it  is  sometimes  practi- 
cable to  take  the  smoothing  cut  at  the  rate  of  1/2  to  1  inch  per  revolu 
tion.  When  a  large  number  of  pieces  of  one  kind  are  to  be  made,  the 
most  economical  speed  and  feed  for  the  work  should  be  determined 
by  the  superintendent  or  an  expert;  otherwise  the  output  may  vary 
with  different  workmen  from  25  to  100  per  cent.  Fig.  239  shows  a 
rotary  measure  adapted  to  measuring  the  speed  of  lathe  work.  In 
measuring  the  speed  of  a  shaft,  for  instance,  the  graduated  wheel  is 
brought  into  contact  with  the  revolving  shaft  and,  in  connection  with  a 
stop-watch,  the  speed  and  feet  per  minute  may  be  read  directly  from 
the  dial  of  the  instrument. 

Miscellaneous.  Meaning  of  the  Word  "  Swing,"  etc.  —  The  planed 
top  of  a  lathe-bed  upon  which  the  lathe-carriage  is  guided  is  called  the 


174 


MACHINE-SHOP  TOOLS  AND  METHODS 


ways  or  shears.  Some  manufacturers  guide  the  lathe-carriage  on  flat 
shears,  but  the  prevailing  form  is  that  of  an  inverted  V,  two  of  these 
V's  being  (generally)  used  to  guide  the  carriage  and  two  to  guide  the 


FIG.  239. 


tail-stock.  The  V's  are  usually  cast  integral  with  the  lathe-bed,  but 
Fig.  240  shows  a  departure  from  the  common  design.  This  illustra- 
tion shows  the  V's,  which  are  made  of  drawn  tool-steel,  mortised  into 
the  lathe-bed.  This  method  of  making  lathe-guides  is  worth  investi- 
gating. 

The  author  has  observed  some  confusion  among  mechanics    as  to 
the  meaning  of  the  word  " swing."     The  word  "swing"  means  the  diam- 


LATHES 


175 


eter  of  work  which,  held  concentric  with  the  spindle  axis,  will  clear  the 
ways.  It  is  important  to  observe  that  a  lathe  will  always  swing  less 
over  the  carriage  or  rest  than  over  the  ways.  It  should  also  be  under- 
stood that  the  terms  used  in  designating  the  length  of  the  lathe  do  not 
indicate  the  capacity  of  the  lafke  between  centers.  For  instance,  a 
16"  X  6'  lathe  means  that  the  lathe  swings  16"  over  the  ways  and 


FIG.  240. 

has  a  bed  6  feet  long,  but  such  a  lathe  will  swing  only  about  10"  over 
the  carriage,  and  take  between  centers  a  shaft  only  about  30"  in  length. 
This  lathe  might  be  used  to  turn  a  pulley  16"  in  diameter  and  3  or  4 
inches  face,  because  the  lathe-carriage  would  not  need  to  pass  under 
the  pulley.  But  a  pulley  of  the  same  diameter  and  having  a  12"  face 
could  not  be  turned  in  a  16"  lathe.  It  might  be  added  that  it  is  not 
considered  economical  to  turn  even  a  narrow-faced  pulley  in  a  lathe 
the  nominal  swing  of  which  is  not  greater  than  the  diameter  of  the 
pulley.  The  reason  is  that  lathes  are  not  ordinarily  built  stiff  enough, 
or  with  sufficient  power,  to  turn  their  full  swing  advantageously.  How- 
ever, the  tendency  is  toward  more  powerful  lathes. 

Purchasing  a  Lathe. — One  very  important  consideration  in  pur- 
chasing a  new  lathe  is  that  the  diameter  of  the  spindle  should  be  amply 
large  for  the  work.  In  the  Michigan  Agricultural  College  there  are  several 
14"x6/  lathes,  of  which  the  front  spindle-bearings  are  27/$"  diameter, 
the  back  bearings  being  proportionally  large.  These  lathe-spindles  are 
hollow — as  all  lathe- spindles  should  be — the  hole  being  l9/ie"  diameter. 
This  large  hole  through  the  spindle  is  a  very  great  advantage  in  turning 
short  pieces  on  the  end  of  a  long  bar.  Having  a  large  hollow  spindle, 
such  work  can,  in  many  cases,  be  passed  through  the  spindle  and  driven 
in  the  lathe-chuck,  the  tail-stock  being  moved  back  out  of  the  way. 


176  MACHINE-SHOP  TOOLS  AND  METHODS 

The  left  end  of  a  bar  being  operated  upon  in  this  way  may  be  supported 
by  any  convenient  means. 

A  lathe,  to  give  the  best  results,  should  have  a  bed  of  ample  propor- 
tions to  resist  flexure  and  torsion,  and  it  should  be  supported  on  a  founda- 
tion of  masonry.  Beds  of  box  form,  with  openings  at  intervals  to 
allow  the  chips  to  drop  through,  are  very  strong  to  resist  the  stresses 
mentioned.  The  metal  around  the  openings  in  the  webs  should  be 
reinforced  by  vertical  ribs  to  compensate  for  the  metal  cut  out.  Some 
years  ago  the  class  in  machine  design  of  which  the  author  is  instructor 
designed  a  lathe  having  a  bed  of  this  form.  The  carriage  of  this  lathe 
is  guided  by  one  V  of  ample  proportions  on  the  front  side,  and  by  a 
flat  way  on  the  rear  side  of  the  bed.  The  tail-stock  is  guided  by  a  flat 
way  on  the  front  side,  and  by  a  V  guide  on  the  rear  side.  This  is  be- 
lieved to  be  a  good  design,  but  it  is  not  original  with  the  author.  With 
respect  to  the  stiffness  of  the  lathe-bed,  it  may  be  observed  that  the 
average  bed  may  be  sprung  perceptibly  by  merely  prying  up  at  one 
corner  by  a  lever  under  the  legs.  This  may  be  easily  proved  in  connec- 
tion with  a  Bath  indicator.  To  make  the  test,  the  indicator  should 
be  held  in  the  tool-post  with  its  finger  in  connection  with  the  lathe 
face-plate.  In  purchasing  a  high-priced  lathe  a  guarantee  as  to  the 
limit  of  error  in  boring  and  facing  should  be  required  of  the  manu- 
facturers. It  should  be  observed,  however,  that  the  most  accurate  lathe 
may  be  twisted  out  of  shape  by  unskillful  adjustment  on  the  foundation. 
Any  lathe  having  a  compound  rest  should  also  have  an  offset  tail-stock 
somewhat  similar  to  that  shown  in  Fig.  214.  'The  object  of  offsetting 
the  tail-stock  is  to  allow  the  compound  rest  a  maximum  arc  of  move- 
ment. 

The  counter-shaft  of  a  lathe  should  also  receive  some  consideration. 
The  pulleys  and  hangers  should  preferably  be  self-oiling,  and  the  cheaper 
forms  of  trappy  clutch-pulleys  should  be  avoided.  Tight  and  loose 
pulleys  with  shifting  belts  give  better  satisfaction  than  a  poor  clutch- 
pulley;  but  a  good,  simple,  durable  clutch-pulley  is  more  convenient 
and  is  better  for  the  belts. 

Testing  the  Lathe -spindle. — After  a  lathe  has  been  used  a  few  years 
it  may  be  found  that  the  spindle  is  slightly  out  of  line,  so  that  it  will  not 
bore  a  parallel  hole.  Fig.  241  illustrates  a  method  of  testing  the  spindle, 
a  and  b  are  two  trams  bolted  to  the  face-plate  of  the  lathe,  a  being 
made  of  metal,  and  B,  for  the  sake  of  lightness,  being  made  of  wood. 
The  center  in  the  main  spindle  should  be  removed  and  tram  a  should 
be  so  made  as  to  project  about  l/z"  beyond  the  face-plate,  b  should 


LATHES 


177 


project  not  less  than  24",  To  test  the  spindle  move  the  tail-stock  until 
its  center  comes  within  reach  of  the  first  tram,  and,  with  tail-stock  and 
tail-spindle  tightly  clamped,  turn  the  face-plate  and  note  whether  the 
tram  revolves  concentrically  wfth  the  center  in  the  tail-spindle.  If  not 
in  line  horizontally,  adjust  the  flail-stock  by  the  set-over  screws  until 
the  tram  clears  equally  at  two  points  horizontally  opposite  around  the 


FIG.  241. 

center.  Move  the  tail-stock  back  and  clamp  as  before,  testing  by  long 
tram.  If  the  spindle  be  in  line  horizontally,  -the  tram  will  clear  the  center 
equally  at  each  side.  If  not  in  line,  it  may  be  possible  to  make  the  cor- 
rection by  placing  strips  of  paper  between  the  V  grooves  of  the  head- 
stock  and  the  V's  of  the  lathe.  The  trams  will  usually  indicate  that  the 
main  spindle  is  also  too  low  and  the  shims  will  raise  it.  If  the  spindle- 
boxes  are  square  or  some  shape  other  than  round,  it  may  be  preferable  to 
adjust  the  spindle  vertically  by  shimming  under  the  boxes.  If  the 
boxes  be  cylindrical,  truing  up  the  spindle  and  making  new  boxes  will 
bring  the  spindle  to  its  original  alinement  without  the  use  of  the 
shims. 

The  cylindrical  part  of  a  lathe-center  is  sometimes  eccentric  to 
the  conical  point.  In  such  a  case  the  trams  must  be  applied  to  the 
conical  part  of  the  center.  The  tail-stock  spindle  may  be  tested  in 
its  two  extreme  positions  in  connection  with  the  long  tram. 


CHAPTER  XII 
TURRET-MACHINES  AND  TURRET-MACHINE  WORK 

Distinguishing  Features  of  the  Turret -machine. — The  slow  processes 
of  the  engine-lathe,  while  still  necessary  in  some  kinds  of  work,  have 
proved  inadequate  to  meet  the  demands  in  many  lines  of  manufacturing. 
In  special  work,  including  short  cylindrical  pieces  of  which  a  great 
many  are  to  be  made  from  one  drawing,  the  turret-machine  is  far  more 
economical.  The  essential  principle  of  a  turret-machine  is  a  tool-holder, 
which  may  be  revolved  upon  its  axis  to  bring  any  one  of  a  number  of  tools 
(usually  six)  into  operation.  Having  only  one  tool-post,  the  engine- 
lathe  necessitates  much  loss  of  time  when  various  operations  are  to  be 
performed  on  the  same  detail.  In  the  turret-lathe  the  tools  for  any  given 
piece  of  work,  having  been  once  adjusted,  may  be  successively  and 
quickly  brought  into  action  until  a  large  number  of  pieces  are  finished. 

The  turret-lathe  was  originally  limited  in  its  adaptation,  but  it  has 
been  modified  and  improved  to  such  an  extent  that  now  the  best  class 
of  these  machines  will  cover  nearly  as  wide  a  range  of  work  as  the  engine- 
lathe.  In  machining  wrought  iron,  steel,  etc.,  on  the  turret-machine 
the  work  is  supplied  with  a  stream  of  oil,  a  tank  and  pump  being  used 
for  this  purpose.  The  cutting  speed  is,  therefore,  higher  than  would  b? 
used  for  the  same  work  in  the  engine-lathe. 

Description  of  a  Plain  Screw-machine. — Fig.  242  shows  a  B.  &  S. 
screw-machine  in  which  the  turret  principle  is  employed.  This  machine 
is  designed  to  make  screws,  studs,  and  various  small  pieces  from  a  bar. 
The  spindle  is  hollow  and  the  bar  is  passed  through  the  spindle  and 
gripped  by  a  chuck.  T  is  the  turret,  having  seven  holes  for  different 
kinds  of  tools,  and  R  is  the  cross-slide  in  which  either  one  or  two  tools  may 
be  used.  The  turret  may  be  moved  longitudinally  by  hand  by  the  turn- 
stile lever  L,  and  automatically  by  the  feed-cones  P  and  feed-rod  and 
gearing  on  the  rear  side  of  the  machine.  In  this  particular  machine 
there  are  eight  changes  of  the  automatic  feed,  varying  from  .005  to  .030 
inch  to  one  revolution  of  spindle.  The  feed-cones  have  only  four  steps, 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


179 


but  for  each  step  there  are  two  speeds,  the  change  being  made  from  fast 
to  slow  by  a  lever  which  operates  mechanism  on  the  rear  side  of  the 
machine.  The  longitudinal  movements  of  the  turret  are  controlled  by 


FIG.  242. 


independent  stops,  which   are   adjusted  for  the  vanous  operations  on 
each  piece  of  work. 


FIG.  243. 

As  indicated,  the  principal  factor  in  the  economical  operations  of 
turret-machines  lies  in  the  turret,  which  holds  in  correct  adjustment  a 


180  MACHINE-SHOP  TOOLS  AND  METHODS 

number  of  tools  which  may  be  quickly  brought  into  operation.  Another 
important  factor,  however,  is  that  the  work,  being  held  in  a  universal 
chuck,  or  a  spring-chuck,  and  turned  from  a  bar,  requires  no  prelimi- 
nary cutting  off  and  centering. 

The  chucks  used  in  many  turret-machines  are  quite  different  from 
those  commonly  used  in  the  engine-lathe.  There  are  various  modifica- 
tions of  these  chucks,  but  the  general  principle  of  chucking  is  clearly 
shown  in  Figs.  243  and  244.  These  figures  show  respectively  the  head- 
stock  of  a  Pratt  &  Whitney  bench-lathe  and  a  chucking-collet  belonging 
to  the  latter.  The  collet  is  split  as  shown  to  admit  of  its  being  closed 


FIG.  244. 

upon  the  stock.  The  conical  shoulder  of  the  collet  fits  the  conical  seat 
in  the  right  end  of  the  lathe-spindle  shown  in  Fig.  243.  The  threaded 
end  of  the  collet  engages  with  the  internal  thread  of  the  hollow  shaft 
passing  through  the  lathe-spindle.  Turning  this  shaft  by  means  of  the 
hand-wheel  shown  on  the  left  draws  the  collet  into  its  seat,  causing  it 
to  grip  the  stock. 

Fig.  245  shows  samples  of  work  done  on  a  screw-machine. 

Making  Filister-head  Screws  in  a  Screw-machine. — If  required  to 
make  a  large  number  of,  say,  l/J'  filister-head  screws,  a  bar  of  machine- 
steel  of  suitable  diameter  would  be  passed  through  the  spindle  and 
gripped  by  the  chuck.  In  passing  the  bar  through  the  chuck  the  distance 
that  it  projects  is  regulated  by  an  adjustable  stop  held  in  one  of  the  tur- 
ret-holes. When  adjusted  to  any  given  length  of  work,  this  stop  regu- 
lates the  projection  of  each  succeeding  piece  to  be  made,  the  stop  being 
moved  out  of  the  way  by  the  motion  of  the  turret  after  each  chucking. 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK  1*1 

The  adjustment  of  the  stock  may  be  considered  the  first  operation. 

The  stop  being  properly  s&,  the  turnstile  lever  is  operated  to  bring 

the  turret-slide  to  the  right,  and  in  this  movement  certain  mechanism  is 


FIG.  245. 


brought  into  operation  which  rotates  the  turret  l/^  of  a  revolution, 
bringing  the  second  tool  into  alinement. 

Probably  the  next  operation  would  be  to  bevel  the  end  of  the  bar 
by  a  tool  held  in  one  of  the  tool-posts.  This  is  very  rapidly  done  by 
a  quick-acting  handle  or  lever  connected  with  the  cross-slide. 

The  third  operation  is  to  feed  the  turret,  bearing  a  roughing-tool 
to  the  revolving  bar.  The  travel  of  this  tool  is  controlled  by  a  stop 
previously  adjusted  for  the  purpose. 

Having  taken  a  roughing  cut,  the  turret-slide  is  quickly  moved  back 
and  rotated  as  before  to  bring  in  line  the  next  tool,  which  is  a  sizer. 


182  MACHINE-SHOP  TOOLS  AND  METHODS 

The  sizer  is  then  fed  up  to  the  stock,  cutting  the  body  of  the  screw 
to  the  right  diameter  for  the  thread. 

For  the  fifth  operation  the  turret-slide  is  moved  back  and  rotated, 
bringing  a  threading-die  in  line,  the  forward  traverse  of  the  turret-slide 
for  this  operation  being  also  controlled  by  a  stop.  Sometimes  two 
dies  are  used,  one  for  roughing  and  the  next  for  sizing  the  thread. 

The  sixth  operation  is  to  chamfer  the  end  of  the  screw.  This  is 
often  effected  by  the  tool  in  the  front  tool-post. 

It  remains  in  the  seventh  operation  to  cut  the  screw  off  to  length. 
This  may  be  accomplished  by  an.  inverted  tool  in  the  rear  tool-post. 
Sometimes  this  tool  is  so  shaped  as  to  round  the  end  of  the  screw  at 
the  same  time  that  it  is  being  cut  off. 

It  must  not  be  inferred  that  the  above  method  is  the  only  method 
of  making  filister-head  screws  on  the  turret-machine.  Different  work- 
men perform  the  same  work  in  different  ways.  In  some  kinds  of  work, 
especially  work  of  irregularly  curved  outline,  forming-tools  are  largely 
used.  Samples  of  such  work  and  the.  methods  connected  therewith 
are  shown  elsewhere  in  this  chapter. 


FIG.  246. 

Automatic  Screw-machine. — Fig.  246  shows   an  automatic  screw- 
machine.     In  this  machine  the  turret  is  placed  on  the  side  of  the  turret- 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


183 


slide  and  its  face  revolves  in  a  vertical  plane.  The  operations  of  the 
chuck,  the  feeding  of  the  bar  stock,  the  reversing  of  the  spindle,  the 
movements  of  the  turret-slide,  are  all  controlled  by  quick-acting  cams. 


FIG.  247. 

The  manufacturers  of  the  machine  furnish  with  each  machine  instruc- 
tions for  laying  out  the  cams.  Full  instructions  for  earning  this  machine 
are  also  given  in  the  September  1903  issue  of  ''Machinery/'  page  6. 

Monitor  Lathe. — The  monitor  lathe  shown  in  Fig.  247  is  adapted 
to  small  gears,  collars,  hand-wheels,  brasswork,  etc.  In  addition  to 
the  turret  it  has  a  vertical  forming  attachment  which  is  seen  mounted 
on  the  cross-slide.  Tools  of  various  shapes  may  be  secured  to  the  slide 
and  fed  to  the  work  by  the  vertical  lever  shown. 

Gisholt  Turret  Chucking-lathe. — As  indicated  in  the  beginning  of 
this  chapter,  turret-machines  have  been  modified  and  improved  to 
such  an  extent  that  the  best  modern  types  cover  almost  as  wide  a  range 


184  MACHINE-SHOP  TOOLS  AND  METHODS 

of  work  as  the  engine-lathe.     Figs.  248  and  249  show  a  machine  which, 
while  designed  primarily  for  multiple  and  broad  cutting  and  heavy  chuck- 


FIG.  248. 


ing-work,  will  also  handle  a  medium  grade  of   work,  including  bar 
.stock  and  thread-cutting.     The  first  of  these  figures  shows  a  machine 


in  operation  upon  a  cone  pulley,  and  the  piece  of  work  shown  in  con- 
nection with  the  second  illustration  resembles  a  compression  coupling. 

To  better  adapt  this  machine  to  the  heavy  stresses  to  which  it  is 
subjected,  the  head-stock,  bed,  and  other  important  members  of  the 
framework  are  made  in  one  casting. 

The  turret,  which  slides  directly  on  the  ways  of  the  bed,  is  made 
massive  and  rigid.  In  common  with  other  turrets  it  is  provided  with 
holes  for  the  reception  of  reamers,  bars,  etc.,  and  in  addition  thereto 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


185 


it  has  six  broad  surfaces  to  which  may  be  bolted  a  great  variety  of  special 
tools  and  fixtures.  This  machine,  is  provided  with  a  carriage  bearing 
a  turret  tool-post  in  which  four  'tools  may  be  used.  Any  one  of  these 
tools  may  be  instantly  brought  irito  action. 

The  machine  is  so  designed  that  the  tools  of  the  main  turret  and 
those  of  the  carriage  may  be  in  operation  at  the  same  time.  Thus, 
in  machining  a  pulley,  for  instance,  the  periphery  of  the  pulley  could 
be  turned  by  tools  in  the  carriage  tool-post  at  the  same  time  that  the 
pulley  was  being  bored  by  the  tools  in  the  main  turret.  When  boring 
with  a  boring-bar  in  the  turret,  one  end  of  the  bar  is  supported  by  a  bush- 
ing in  the  main  spindle  of  the  machine.  This  arrangement  gives  extra 
rigidity  to  the  boring-bar. 

The  Hollow  Hexagon  Turret-lathe.  ^  Fig.  250  shows  a  machine 
known  as  the  hollow  hexagon  turret-lathe.  As  indicated  by  its  title 


FIG.  250. 


the  turret  in  this  machine  is  hexagonal,  the  tools  being  clamped  to 
the  outer  faces  of  the  turret.  The  open  top  admits  of  the  tools  and 
fixtures  being  bolted  from  the  inside  of  the  turret,  without  taking  up 
any  room  on  the  outside  for  the  bolt-heads,  etc.  This  machine  is  pro- 
vided with  roller  feed,  independent  stops,  automatic  chucks,  etc. 

Fig.  251  shows  the  spindle  projecting  through  the  front  bearing. 
The  head  for  holding  the  chuck-collets  is  forged  on  the  end  of  the  spindle, 
giving  a  minimum  of  overhang  to  the  gripping  mechanism.  The 


186  MACHINE-SHOP  TOOLS  AND  METHODS 

arrangement  is  such  that  the  collets  may  be  conveniently  removed 
from  the  outer  end  of  the  spindle  without  disturbing  the  chuck.  This 
machine  has  a  capacity  of  turning  from  bar  stock  work  not  greater 


FIG.  251. 

than  2"  diameter  by  24"  long.  It  swings  over  the  bed  16",  thus 
admitting  of  the  machining  larger  work  of  short  length. 

The  Flat  Turret-lathe. — Fig.  252  shows  the  machine  known  as  the 
flat  turret-lathe.  This  machine  is  of  the  same  capacity  as  that  last 
described.  The  names  of  the  leading  parts  are  given  in  connection 
with  the  illustration. 

The  turret  which  is  shown  in  Fig.  253  bears  but  little  resemblance 
to  that  of  common  form,  and  it  is  called  a  flat  turret  to  distinguish  it 
from  the  latter.  The  turret  is  mounted  on  a  low  carriage,  being  held 
to  the  carriage  by  an  annular  gib.  The  carriage  slides  on  V's  on  top 
of  the  bed  and  is  gibbed  to  the  outer  edges  of  same.  The  tool-holders 
have  little  or  no  overhang,  and  the  whole  design  of  the  turret  is  such 
as  to  afford  great  rigidity.  The  automatic  traverse  of  the  carriage  is 
operated  by  a  worm-wheel  and  worm.  The  worm,  which  is  held  in 
mesh  with  the  worm-wheel  by  a  latch,  is  automatically  disengaged 
by  the  feed-stops.  The  stops  are  shown  projecting  beyond  the  right 
end  of  the  machine.  There  is  one  of  these  stops  for  each  tool-holder 
of  the  turret,  and  they  are  independently  adjustable.  By  automatic 
mechanism  the  turret  is  rotated  to  bring  the  next  required  tool  into 
operation  as  soon  as  it  clears  the  work  in  its  backward  traverse.  The 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK  187 


I 


190 


MACHINE-SHOP  TOOLS  AND  METHODS 


pin  which  locks  the  turret  in  position  is  placed  at  a  maximum  distance 
from  the  center  of  the  turret,  the  arrangement  being  such  as  to  reduce 
the  lost  motion  to  practically  zero. 

The  Cross-slide. — Fig.  254  shows  a  cross-slide  used  in  connection 
with  the  turret.  In  addition  to  the  cutting-off  tool  commonly  used  in 
one  side  of  the  cross-slide,  various  forming-tools  and  other  special  tools 
may  be  held  on  the  opposite  side.  The  tools  are  brought  in  contact 
with  the  work  by  the  long  lever  shown. 

The  apparatus  furnished  with  the  flat  turret-machine  admits  of  a 
wide  range  of  operations,  but  it  is  sometimes  advantageous  to  make 
special  fixtures  for  special  work.  Several  of  these  machines  are  in 
operation  in  a  plant  within  a  minute's  walk  of  the  office  where  this  book 
was  written,  and  the  officials  of  the  Omega  Separator  Company  kindly 
permitted  the  author  to  observe  the  operations  of  these  and  other  turret- 
machines.  He  noticed  a  special  cross-slide  which  was  made  at  the  plant 
and  used  in  connection  with  separator  bowls.  This  slide  has  two  tool- 
holders.  The  first  tool-holder  carries  a  formed  cutter  and  a  cutting-off 
tool  which  rough-turns  the  piece  and  cuts  off  a  projecting  end.  When 
this  roughing  is  completed  the  cross-slide  is  fed  in  the  opposite  direction, 
fringing  the  finishing- tool  in  contact  with  the  work. 


CLOSED 


OPEN 


FIG.  255. 

Automatic  Chuck  and  Roller  Feed. — Sectional  views  of  the  auto- 
matic chuck  are  shown  in  Figs.  255  and  256.  This  chuck  grips  round, 
hexagon,  and  other  shapes  usually  handled  in  a  turret-machine.  The 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


191 


first  of  these  figures  shows  the  chuck  closed,  and  the  second  shows  it 
open.  Fig.  257  shows  the  roller-feed  mechanism.  When  the  chuck 
is  open  the  feed  mechanism  advances  the  stock  through  the  spindle 


FIG.  257. 

and  chuck  until  it  comes  in  contact  with  a  stop  attached  to  the  front  of 
the  carriage.  It  is  set  in  motion  by  the  same  lever  that  controls  the 
chuck.  The  rollers  are  held  in  contact  with  the  stock  by  stiff  springs 
which  admit  of  slippage  when  the  bar  meets  the  stop. 

The  Die -carriage. — In  addition  to  the  pro  vision  for  holding  threading- 
dies  on  the  turret,  the  machine  is  furnished  with  a  die-carriage  in  which 
thread-dies  of  any  kind  may  be  held.  This  carriage  is  mounted  on  a 
sliding  bar,  as  shown  at  D  in  Fig.  258,  and  may  be  swung  into  working 
position  by  means  of  the  lever  at  its  top. 

Improvements  in  the  Flat  Turret-lathe. — This  machine  has  been 
recently  redesigned,  a  side  view  of  the  new  machine  being  shown  in 


194 


MACHINE-SHOP  TOOLS  AND  METHODS 


Fig.  259.  The  latest  construction  admits  of  such  a  close  approximation 
to  the  processes  of  the  engine-lathe  that  in  many  kinds  of  work  the 
tools  of  the  engine-lathe  may  be  used.  This  makes  it  possible  in  many 


FIG.  260. 

cases  to  machine  single  pieces  as  cheaply  as,  or  more  cheaply  than,  in  an 
engine-lathe.  The  alterations  in  the  machine  are  such  as  to  adapt  the 
machine  also  to  common  chuck  work.  The  head-stock,  which  was  fixed 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK  195 

rigidly  to  the  bed,  has  been  given  a  crosswise  movement,  and  in  connec- 
tion with  this  movement  a  series,  of  stops  similar  in  principle  to  those 


FIG.  261. 


used  in  the  turret  are  used.     The  stops  are  seen  projecting  from  the 
left  side  of  the  machine  in  Fig.  260.      The  crosswise  movement  of  the 


head-stock  is  effected  by  the  turnstile  lever  shown  in  Fig.  259.     This 
movement  is  wholly  on  one  side  of  the  center  line,  the  head-stock  being 


196 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  263. 


FIG.  264. 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


197 


returned  to  a  fixed  stop  when  reamers  and  other  tools  of  this  character 
are  used.     Both  head-stock  and  "turret-slide  are  provided  with  power 


FIG.  265. 


FIG.  266. 


feed.     Friction  mechanism  is  used  to  operate  the  power  feed,  the  rate 
of  feed  being  adjusted  by  a  graduated  hand-wheel  shown  under  the 


198 


MACHINE-SHOP  TOOLS  AND  METHODS 


head-stock  turnstile  lever.  The  combination  of  the  longitudinal  move- 
ment of  the  turret  and  the  crosswise  movement  of  the  head-stock,  in 
connection  with  the  stops  for  both,  admits  of  machining  with  the  same 
tool  two  surfaces  which  meet  in  a  corner. 

The  Geared  Head. — Instead  of  the  cone-pulley  drive  for  the  main 
spindle  a  system  of  gears  giving  the  various  spindle  speeds  is  employed, 
the  changes  being  made  by  levers.  This  gearing  is  operated  by  a  single- 
face  pulley,  as  shown  in  Fig.  259.  The  machine  may  be  driven  with 
equal  facility  either  by  a  counter-shaft  or  an  electric  motor. 

Examples  of  Work  Done  on  the  Improved  Machine. — Figs.  261,  262, 
263,  264,  265,  and  266  show  various  operations  indicating  the  adaptability 
of  the  new  machine  to  chuck  work,  the  long  cross-bar  shown  in  the  last 
three  figures  being  particularly  noticeable.  Fig.  264  shows  three  cuts 
being  taken  simultaneously  with  the  cross-bar,  and  Fig.  265  shows  the 
cross-bar  facing  both  edges  of  a  pulley  in  one  operation. 

Turrets  as  Used  on  Engine-lathes. — The  turret-machine  has  proved 
so  advantageous  that  many  engine-lathes  are  now  furnished  with  turrets. 


FIG.  267. 

Fig.  267  shows  a  turret  engine-lathe.  The  turret  of  this  machine  has 
crosswise  and  longitudinal  feeds,  these  being  effected  automatically  by 
the  regular  carriage-feed  mechanism. 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


199 


Fig.  268  shows  a  turret  adapted  for  use  on  the  ways  of  an  engine- 
lathe.  » 

The  turret  shown  in  Fig.  269  isklesigned  to  be  held  on  top  of  the  tool- 
rest  of  a  lathe  the  same  as  a  tool-post  is  held.  The  turrets  illustrated  in 


Figs.  267,  268,  and  269  may  be  detached,  when  the  lathe  may  be  used 
as  an  ordinary  engine-lathe. 


200 


MACHINE-SHOP  TOOLS  AND  METHODS 


TOOLS    USED    IN  THE  TURRET-MACHINE 

Box  Tools. — One  characteristic  of  the  turret-machine  is  its  use  of 
box   tools.     Fig.  270   shows    a   simple  design  of   box   tool  which  was 


FIG.  269. 

suggested  by  C.  H.  Ramsey  in  "  American  Machinist/'  vol.  27,  page  61. 
The  tool  B  fits  in  a  slot  in  the  end  of  the  tool-holder  and  is  clamped  as 
shown.  The  back  rest  F,  which  supports  the  pressure  of  the  cut,  also 
fits  in  a  slot,  and  both  cutter  and  back  rest  are  adjustable.  This  holder 
is  made  from  round  stock,  and  the  small  end  fits  in  one  of  the  turret- 
holes.  With  slightly  more  expense  the  back  rest  could  be  placed  at 
an  angle  as  shown  in  Fig.  271,  and  this  arrangement  furnishes  a  better 
support  to  the  cutting-tool.  In  using  box  tools  on  rough  stock  the 
cutting-tool  is  usually  placed  slightly  in  advance  of  the  back  rest.  The 
cutter  B  in  Fig.  270  is  so  placed.  This  arrangement  provides  for  cutting 
a  true  bearing  for  the  rest.  On  smooth  stock,  such  as  round  cold-rolled 
bars,  the  rest  is  usually  placed  in  advance  of  the  tool. 

A  box  tool  having  two  cutters  is  shown  in  Fig.  272.      These  cutters 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


201 


may  be  adjusted  for  two  different  diameters,  the  forward  tool  making 
the  larger  diameter  and  the  rear -tool  the  smaller  diameter. 


FIG.  272. 


In  the  roughing  box  tool  shown  in  Fig.  273  the  cutting-tool  is  held 
in  a  tool-post  similar  to  the  tool-post  of  an  engine-lathe,  and  it  is  so 
,  adjusted  in  relation  to  the  work  as  to  take  a  shearing  cut.     The  back 
rest  is  made  in  two  parts  to  admit  of  more  accurate  adjustment. 


202 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  tool  shown  in  Fig.  274  is  called  a  Knee-tool.      It  is  used  mostly 
on  cast  iron. 


FIG.  273. 


FIG.  274. 


FIG.  275. 


Fig.  275  shows  a  Hollow  Mill,  which  is  sometimes  used  instead  of  a 
roughing  box  tool  in  the  turret-machine.  It  may  be  adjusted  by  the 
collar  and  set-screw  shown. 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK          203 


FIG.  279. 


FIG.  280. 


204 


MACHINE-SHOP  TOOLS  AND  METHODS 


Drills  may  be  held  in  a  plain  holder  one  end  of  which  fits  the  drill 
and  the  other  end  a  hole  in  the  turret,  or  they  may  be  held  in  a  drill- 
chuck  like  that  of  Fig.  276. 


FIG.  281. 


Thread-cutting  in  the  Turret-lathe. — Thread  is  usually  cut  in  the 
turret-machine  with  a  die.  Figs.  277  and  278  show  respectively  a  die 
and  a  releasing  die-holder. 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK 


205 


The    Spring-die   shown   in    Fig.  279  may  be  adjusted  by  the  split 
collar.     This  die  is  also  held  in  the  holder  of  Fig.  278. 

The  Geometric  Screw-cutting  Die-head  illustrated  in  Fig.  280  is 
self-opening  and  adjustable.  Ae  small  end  or  shank  which  enters  a 
hole  of  the  turret  is  hollow  and  admits 
of  cutting  any  length  of  screw  within  the 
capacity  of  the  machine  upon  which  it  is 
used.  Stopping  the  travel  of  the  turret- 
slide  automatically  opens  the  die.  It  is 
closed  again  by  the  handle  shown,  or  by 
automatic  connection. 

Forming-tools. — In  Fig.  281  is  shown 
a  forming-tool  T  secured  to  the  cross- 
slide  of  a  Garvin  Universal  screw-machine. 
One  end  of  the  piece  to  be  turned  is  sup- 
ported in  a  center-rest  held  in  one  of  the 
turret-holes.  An  adjustable  center-rest  is  shown  in  Fig.  282. 


FIG.  282. 


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------  ,  — 


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.Vww.vw- 

33 

\  —  * 

-£• 


5 


FIG.  283. 

A  great  variety  of  forming-tools  are  used  in  connection  with  turret- 
machines,  and  Fig.  283  shows  samples  of  forming-tool  work. 


206 


MACHINE-SHOP  TOOLS  AND  METHODS 


Fig.  284  shows  one  of  the  ''turners"  used  in  connection  with  the 
turret  of  the  flat  turret-lathe.     The  cutter  of  this  turner  is  held  in  a 


FIG.  284. 


FIG.  285. 

pivoted  tool-block  the  frame  of  which  is  secured  to  the  turret.      By 
means  of  an  adjusting-screw,  work  from  0  to  2  inches  diameter  may  be 


TURRET-MACHINES  AND  TURRET-MACHINE  WORK  207 

turned  after  the  tool  has  been  clamped.  To  prevent  the  work  from 
being  marked,  when  the  turret-slide  is  moved  back,  the  tool  may,  by 
means  of  the  spherical  end  lever,  shown,  be  withdrawn. 

A  Taper  Turner  and  Former  used  on  the  machine  last  referred  to 
is  shown  in  Fig.  285.  The  cutting-tool  and  back  rest  are  controlled 
by  the  former  or  template,  which  is  planed  tapering  in  thickness  and 
width,  thus  forming  two  wedges,  one  of  which  controls  the  cutting-tool 
and  the  other  the  back  rest.  This  turner  turns  tapers  and  other  forms, 
a  different  template  being  used  for  each  different  form. 


CHAPTER   XIII 
LATHE-  AND  PLANER-TOOLS 

A  Standard  Set  of  Lathe-tools. — The  term  machine-tool  refers  to  the 
machine  proper,  as,  for  instance,  the  lathe  or  the  planer.  The  terms 
lathe-tool  and  planer-tool  have  reference  to  the  steel  tools  used  to  cut 


FIG.  28G. 

the  metal.  These  tools,  which  do  not  include  those  ot  the  turret-lathe, 
are,  with  rare  exceptions,  held  in  the  tool-post  or  tool-block  of  the  com- 
mon lathe  or  planer.  In  Figs.  286  and  287  we  show  a  standard  set  of 
lathe-tools,  the  names  of  which  are  as  follows:  No..  1,  left-hand  side  tool : 
No.  2,  right-hand  side  tool;  No.  3,  bent  right-hand  side  tool;  No.  4, 
roughing-tool ;  No.  5,  finishing-tool;  No.  6,  diamond-point  tool;  No.  7, 

208 


LATHE-  AND  PLANER-TOOLS 


209 


round-nose  tool;    No.  8,  cutting-off  tool;    No.  9,  thread-tool;    No.  10, 
bent  thread-tool;  No.  11,  inside  -thread-tool ;   No.  12,  boring- tool. 

I 


FIG.  287. 


The  above  list  of  tools  is  referred  to  as  a  standard  set;  but  there 
is  no  standard  that  is  generally  recognized,  and  we  show  in  Fig.  288 


FIG.  288. 


twelve  lathe-tools  which  are  regarded  as  a  regular  set  by  other  authori- 
ties. These  are  named  as  follows:  No.  1,  left-hand  side  tool;  No.  2, 
right-hand  side  tool;  No.  3,  right-hand  bent;  No.  4,  right-hand  dia- 
mond-point; No.  5,  left-hand  diamond-point;  No.  6,  round-nose;  No.  7, 


210 


MACHINE-SHOP  TOOLS  AND  METHODS 


«utting-off;  No.  8,  threading;  No.  9,  bent  threading;  No.  10,  rough- 
Ing;  No.  11,  boring;  No.  12,  inside-threading.  Of  the  latter  Nos.  1, 
.2,  3,  7,  11,  and  12  are  intended  to  be  of  the  same  shape  respectively 
as  Nos.  1,  2,  3,  8,  11,  and  12  in  the  first  set.  The  threading-tools  in 
both  sets  are  the  U.  S.  standard. 


Uses  of  Various  Lathe-tools.— Respecting  the  use  of  the  tools  in 
Fig.  288,  No.  1  is  suitable  for  facing  or  turning  the  left  side  of  a  collar, 
as  shown  in  the  plan  at  (1)  in  Fig.  289,  while  No.  2  is  used  for  facing 
the  right  side  of  same,  or  the  right  end  of  a  shaft.  These  tools  may 
also  be  used  for  facing  at  other  angles  than  those  shown.  Tool  No.  3 


LATHE-  AND   PLANER-TOOLS  211 

is  designed  for  facing  on  the  right  side  close  to  the  lathe  face  plate.  It 
is  bent  in  order  to  permit  the  tto"bl -rest  to  clear  the  lathe-dog,  as  at  (3). 
The  diamond-point  tools  (4)  andjj,5)*  are  used  to  take  roughing  cuts,  the 
top  face  of  No.  4  being  inclined  toward  the  right,  making  it  cut  more 
freely  on  the  left  of  the  shoulder.  The  cutting  directions  of  these  tools  are 
shown  at  (4)  and  (5)  in  Fig.  289.  The  diamond-point  tool  may  be  used,  also, 
for  smoothing  or  finishing  cuts  (small  cuts,  about  .01"  deep)  by  adjusting 
it  so  that  one  side  will  have  nearly  flat  contact  with  the  work,  as  at  (5a). 
It  should  touch  near  the  point,  as  indicated  by  the  arrow.  The  tool 
marked  (6)  may  be  used  for  rounding  out  a  fillet,  and  for  similar  pur- 
poses": see  (6)  in  Fig.  289.  No.  7,  as  its  name  indicates,  is  used  for  cutting 
off  a  shaft,  this  operation  being  shown  at  (7).  For  ordinary  work  it 
should  be  1/ie  to  1/g  inch  wide.  It  may  also  be  used  for  smoothing  cuts 
and  for  squaring  a  corner  under  a  collar.  For  these  purposes  it  is  usually 
made  about  3/ie"  wide.  By  grinding  No.  7  with  proper  side  clearance  it 
may  be  used  to  cut  square  threads.  No.  8  is  designed  for  thread-cutting, 
but  when  the  thread  is  near  the  face-plate  end  of  the  work  No.  9  should 
be  used.  These  two  tools  are  held  in  the  tool-post  like  Nos.  7  and  3 
respectively.  No.  10  is  used  by  some  mechanics  for  rough  cuts,  instead 
of  Nos.  4  and  5;  it  may  also  be  used  for  cutting  on  the  end  of  a  shaft,  or 
other  such  work,  when  there  is  too  much  metal  for  one  of  the  side  tools 
shown.  The  side  tools  described  are  used  mainly  for  the  light  smoothing 
cuts.  For  internal  work  we  use  No.  11  for  boring  and  No.  12  for  threading, 
as  shown  at  (11)  and  (12)  in  the  illustrations  of  Fig.  289.  For  squaring 
up  a  shoulder  the  boring-tool  is  shaped  like  (lla).  The  angle  A  of  this 
tool  should  be  less  than  90°  to  insure  reaching  the  extreme  corner,  and 
also  to  lessen  the  tendency  to  chatter.  By  grinding  this  tool  with  the 
proper  clearance,  it  may  be  used,  also,  for  internal  square  threads.  Some 
mechanics  prefer  the  tool  shown  at  (13)  to  the  diamond-point  tool  for 
heavy  work.  This  is  a  very  strong  and  otherwise  efficient  tool.  For 
smoothing  cuts  and  very  fast  feeds  (14)  shows  a  good  design. 

Planer-tools.— Of  the  tools  shown  in  Figs.  288  and  289,  Nos.  1,  2,  3, 
•4,  5,  6,  7, 10, 13,  and  14  are  also  used  on  the  planer  in  the  same  manner 
that  they  are  used  in  the  lathe.  For  roughing  down  vertical  faces  the 
stocking -tool,  No,  15,  Fig.  289,  is  a  good  form.  Various  special  tools  are 
made  for  both  planer  and  lathe;  these  have  special  shapes  to  suit  the 
requirements  of  each  case. 

Tools  for  Brass  work. — The  tools  in  Fig.  288  are  adapted  to  all  the 
metals  in  common  use  except  brass.  Nos.  7  to  12  inclusive  may  be  used 

•*  This  shape  is  somewhat  difficult  to  forge  and  is  not  as  much  used  as  formerly. 


212 


MACHINE-SHOP  TOOLS  AND  METHODS 


for  brass  if  the  top  cutting  face  be  kept  flat  and  horizontal.  In  addition 
to  these,  the  tool  illustrated,  Fig.  290,  may  be  used  on  brass  for  longi- 
tudinal and  crosswise  roughing  and  finishing  cuts.  For  squaring  under 


FIG.  290. 


FIG.  291. 


a  shoulder  the  cutting  edges  of  this  tool  should  be  ground  to  a  point, 
and  somewhat  less  than  90°. 

Fig.  291  shows  the  top  view  of  a  brass  tool  which  is  used  by  some 
mechanics  for  longitudinal  and  cross  feeds.  This  tool  should  be  flat 
on  top  and  have  clearance  on  the  front  end  and  on  the  concave  side. 

Tool -holder  Plan. — The  foregoing  system,  in  which  the  tools  are  forged 
from  bar  stock,  is  being  superseded  to  a  considerable  extent  by  the  tool- 
holder  plan.  In  this  system  a  number  of  tool  steel  cutters  are  used  inter- 
changeably in  one  holder,  the  latter  being  made  of  cheaper  metal.  These 


FIG.  292. 


FIG.  293. 


cutters  are  made  of  sizes  and  shapes  which  are  kept  in  stock  in  all  grades 
of  tool-steel  by  the  dealers.  The  cutters  require  no  forging,  being  ground 
on  the  emery-wheel  to  any  ordinary  shape.  Self-hardening  steel  is 
generally  used  for  the  cutters,  and  this  requires  no  tempering. 

Fig.  292  shows  a  tool  holder  and  cutter.  The  cutters  are  held  by  a 
set-screw  at  an  angle  which  is  considered  about  right  for  average  require- 
ments. Generally  it  is  not  necessary  to  grind  the  top  faces  of  these 


LATHE-  AND  PLANER-TOOLS 


213 


cutters,  but  they  may  be  ground  to  give  negative  or  zero  rake  for  brass- 
work,  or  be  changed  for  any  o>ther  special  case.     The  uses  of  these  tools 


FIG.  294. 


FIG.  295. 


FIG.  296. 


in  various  ways,  both  for  lathe  and  planer  work,  are  shown  in  Figs.  293, 
294,  295,  and  296. 

Boring-tool  Attachment  for  Lathes — Boring  Deep  Holes. — A  very 

substantial   boring   device   is   shown  in   Fig.   297.     In   this   device  A 
is  a  kind  of  clamping  fixture,  which  takes  the  place  of  the  ordinary 

Cutter-bar  attachment  for  lathes 


FIG.  297. 

tool-post,  being  held  on  the  lathe-rest  by  the  bolts  B.     The  tools  or 
cutters  are  secured  in  either  end  of  the  bar  or  tool-holder,  as  shown 


Cutter-bar 


f) 


FIG.  298. 

in  Fig.  298.  The  fixture  A  will  hold  different  sizes  of  bars,  which 
are  clamped  by  the  set-screws  S  and  movable  jaw  J.  The  overhang  of 
the  bars  may  be  gaged  to  suit  the  length  of  hole. 

When  boring  extra  long  holes  with  a  common  boring-tool,  the  springing 
of  the  tool  makes  the  hole  tapering.  To  compensate  for  this  error  the 
experienced  mechanic  feeds  the  lathe-carriage  both  forward  and  back- 
ward, and  takes  very  light  cuts  to  bring  the  hole  to  the  finished  size. 


214  MACHINE-SHOP  TOOLS  AND  METHODS 

A  reamer  would,  of  course,  save  time,  but  such  a  tool  is  not  always 
available  for  special  sizes.  The  device  shown  in  Fig.  297  is  much 
superior  to  the  ordinary  boring-tool.  By  making  the  cutter  with  two 
cutting  edges  (one  on  each  end),  and  taking  a  double  cut,  the  bar  is 
braced  against  deflection  and  parallel  boring  is  made  easy.  The  author 
has  sometimes  used  double  cutters  instead  of  a  reamer.  For  this  purpose 
the  cutter  should  be  turned  in  its  bar  between  centers.  To  prevent 
chattering  and  make  a  smooth  hole,  the  cutter  should  be  filed  with  mini- 
mum heel  clearance,  and  after  being  tempered  it  should  be  carefully 
oilstoned.  If  the  cutter  be  held  with  a  taper-pin  fitting  a  notch  near 
the  center  of  the  cutter,  it  may  be  very  quickly  adjusted  in  the  bar. 
Cold-rolled  steel  or  tool  steel,  used  without  being  machined,  will  answer 
for  the  bars. 

Planer-tool  with  Angular  Adjustment. — Any  of  these  tools,  except- 
ing the  boring-tool,  may  be  used  on  the  planer;  but  the  tool  shown  in 


FIG.  299.  FIG.  300. 

Fig.  299  is  specially  adapted  to  planer  work.  Fig.  300  indicates  how 
this  tool  may  be  adjusted  to  different  angles  in  the  latter  work. 

Gang  Planer-tool. — This  tool,  which  is  illustrated  in  Fig.  301,  is 
designed  especially  for  planing  broad  fiat  surfaces.  The  tool-head, 
carrying  several  cutters,  is  adjustable  on  the  shank.  By  properly 
adjusting  the  head  a  coarser  feed  as  compared  with  a  single  cutter 
may  be  used.  This  is  accomplished  by  dividing  the  cut  as  shown  in 
Fig.  302.  With  a  given  feed,  say  Vg",  the  head  should  be  so  ad- 
justed as  to  divide  the  cut  equally  between  the  number  of  cutters  used. 
The  cutters  should  be  ground  to  uniform  shape,  and  should  be  so  set 
as  to  bring  the  lower  ends  in  the  same  horizontal  plane,  a  flat  plate  or 
surface  being  used  for  this  purpose. 

Figs.  303  and  304  show  a  side  tool  and  a  cutting-off  tool  respec- 
tively. These  may  be  used  for  both  planer  and  lathe  work.  When  the 
holders  are  offset  they  are  better  adapted  to  lathe  work. 


LATHE-  AND  PLANER-TOOLS 


215 


Thread-tool  and  Holder. — In  Fig.  305  is  shown  a  good  design  of 
tool  for  thread-cutting.  The  cutter,  which  is  held  by  the  two  set-screws 
as  shown,  is  shaped  to  the  angle  .of  the  U.  S.  standard  thread  (60°)  and 


FIG.  303. 


STRAIGHT    CUT    OFF     TOOL 


FIG.  301. 


FIG.  302. 


FIG.  304. 


is  to  be  ground  on  the  top  face  only.  The  cutter  should  be  so  ground  and 
set  that  a  line  coincident  with  its  top  face  would  pass  through  the  axis 
of  the  central  clamping-screw  and  be  parallel  with  the  bottom  of  the 
holder.  The  same  line  should  pass  through  the  axis  of  the  work. 

The  Rivett-Dock  Thread -tool. — In  cutting  threads  with  one  single- 
pointed  tool,  or  even  with  one  roughing  and  one  finishing  tool,  considerable 
time  is  expended  in  grinding  the  tools 
to  a  gage,  adjusting  them  in  the 
lathe,  and  in  gaging  the  work. 
The  thread- tool  shown  in  Fig.  306 
is  designed  to  overcome,  in  a  great 
measure,  these  difficulties.  For  each 
pitch  of  thread  a  disk  cutter,  having  a  number  of  teeth  of  the  cor- 
rect angle,  is  furnished.  These  disks  are  interchangeable  and  may  be 
secured  to  a  holder  which,  when  in  use,  is  mounted  on  the  tool-block  cf 
the  lathe  as  shown.  Each  tooth  traverses  the  thread  once,  the  first 
cut  being  made  by  tooth  No.  1,  the  second  by  No.  2,  and  so  on,  until 
all  the  teeth  in  the  disk  have  been  brought  into  contact  with  the  thread. 
The  last  tooth,  which  is  the  only  one  that  conforms  to  the  final  shape 
of  the  thread  (the  others  being  broader  at  the  point) ,  cuts  the  thread  to- 
the  required  shape  and  diameter. 

Each  tooth  is  brought  into  position  in  turn,  by  the  lever  shown. 


FIG.  305. 


FIG.  306. 


216 


LATHE-  AND   PLANER-TOOLS 


217 


By  means  of  this  lever  and  its  ingenious  connections,  the  disk  is  rotated, 
advanced  to  the  work,  and  locked  "for  each  cut. 

For  extra-accurate  threading,  ^uch  as  is  necessary  in  making  taps, 
and  for  fine  finish,  it  may  be  necessary  to  divide  the  last  cut  into  two 
or  more  finer  cuts.  The  tool  is  provided  with  micrometer  adjustment  for 
this  purpose.  It  is  furnished,  also,  with  side-rake  adjustment  for  right 
and  left  threads. 

Multiple -edge  Tools.  —The  tool  above  described  might  be  called  a 
turret  thread-tool,  the  principle  of  action  being  that  of  the  turret- 
machine.  In  the  chaser-edge  cutter,  Fig.  307,  the  holder  of  which 


FIG.  308. 


is  shown  in  Fig.  308,  all  of  the  teeth  are  in  contact  with  the  thread  at 
the  same  time.  This  reduces  the  wear  on  each  tooth  and  accomplishes 
some  of  the  purposes  of  the  tool  shown  in  Fig.  306. . 

The  possibilities  of  multiple-edge  tools  are  not  fully  appreciated. 
These  tools  may  be  used  for  lathe,  planer,  shaper  work,  etc.  If,  for 
instance,  three  grooves  were  required  to  be  cut  in  a  shaft,  a  cutter  and 
tool-holder  could  easily  be  made  (and,  indeed,  is  sometimes  made)  to 
cut  all  the  grooves  in  one  operation.  A  tool  could  as  easily  be  made 
to  cut  several  grooves  simultaneously  in  the  planer  or  shaper. 

Fig.  309  shows  a  piston-ring  being  turned  on  the  inside  and  outside 
in  one  operation.  Two  boring-bars,  each  carrying  an  adjustable  cutter, 
are  used  in  this  case.  A  forked  tool-holder  with  cutters  held  by  set- 
screws  is  sometimes  used  for  work  of  this  character.  Fig.  310  shows 
such  a  holder,  but  the  adjustable  cutters  are  held  by  a  plate  and  one 
screw.  Fig.  301  might  be  classed  with  multiple-edge  tools. 

Advantage  of  Backward  Offset  in  Planer-tools. — Fig.  311  *  shows  a 

*  Cut  first  used  to  illustrate  an  article  by  "Theodore"  in  "American  Machin- 
ist," vol.  27,  page  290. 


218 


MACHINE-SHOP  TOOLS  AND  METHODS 


tool-holder  and  cutter  designed  for  planing  lathe  Vs.      When  the  cutting 
edge  of  the  tool  has  a  broad  bearing  on  the  work  this  backward  offset 


FIG.  309. 


has  an  important  advantage.      The  strongest  tool-holder  must  spring 
to  a  slight  degree,  but  when  it  is  made  as  above  it  springs  from  the 


Wtf- 


ni 
3 
I  ' 

•f                 1 

lilll 

ill 

# Square  Steel 


%  Cap  Screw 


FIG.  310. 


work,  and  this  in  a  large  measure  prevents  chattering.  This  tool  shows 
how  cutters  for  shaping  large  curves  and  other  forms,  may  be  made 
very  cheaply.  The  cutter  requires  but  a  small  piece  of  high-grade  steel 


LATHE-  AND  PLANER-TOOLS 


219 


and  it  is  held  by  one  bolt  and  a  dowel-pin  as  shown.     Any  number  of 
cutters  may  be  used  separately  in"  the  same  holder. 


FIG.  311. 

Spring-tools  for  Lathe -work. — The  principle  of  the  above  tool  is 
sometimes  employed  in  a  lathe-tool.     For  lathe  work,  however,  the  tool 
is  shaped  as  shown  in  Fig.  312, 
which  represents  a  spring  thread- 
tool. 

Rake  and  Clearance  of  Lathe - 
tools. — One  of  the  most  impor- 
tant considerations  in  connection 
with  lathe-  and  planer-tools  is  the 
proper  inclination  of  the  cutting 
face  to  the  work.  For  most  pur- 
poses the  tools  should  be  so  shaped 
as  to  peel  the  metal  off,  somewhat 
as  a  plow  turns  the  soil.  When  a 
tool  is  so  shaped  as  to  produce  this 
effect  it  is  said  to  have  "rake." 
A  more  precise  explanation  of  the 

use  of  the  term  rake  is  given  in  connection  with  the  illustrations  in  Figs. 
313,  314,  and  315.  Referring  to  these  figures,  Fig.  313  is  a  side  view  of  a 
cylinder  or  shaft  as  held  between  lathe-centers,  and  in  connection  with 
same  is  seen  a  vertical  section  through  CD,  Fig.  314,  of  a  side  tool. 


FIG.  312. 


220 


MACHINE-SHOP  TOOLS  AND  METHODS 


Fig.  315  is  a  cross-section  of  a  cylinder  with  a  longitudinal  vertical 
section  of  a  lathe-tool.  Assuming  in  all  cases  that  the  point  of  the 
tool  is  set  on  a  level  with  the  axis  of  the  lathe-spindle,  in  Fig.  313  the 


FIG.  313. 


FIG.  314. 


angle  A,  formed  by  the  horizontal  line  H  and  face  F  of  the  tool,  will, 
in  this  work,  be  called  right  rake,  while  the  angle  A  1,  between  the  ver- 
tical line  V  and  side  S,  will  be  called  right  clearance.*  The  similar 
angle  and  clearance  on  the  opposite  side  (not  shown)  will  be  called 
left  rake  and  left  clearance.  In  Fig.  315  the  angle  A  2,  formed  by  the 
horizontal  line  H  passing  through  center  of  the  shaft,  and  by  the  top 
face  F  1  of  the  tool,  will  be  called  front  rake;  the  angle  A  3,  between 
the  vertical  line  V  1  and  the  front  side  of  the  tool  S  1,  will  be  called 
heel-clearance,  and  the  angle  between  front  side  S  1  and  the  top  face 
F 1  will  be  called  the  cutting  angle.  The  above  explanations  refer 
to  the  lathe- tools.  The  rake  and  clearance  on  planer-tools  are  meas- 
ured from  vertical  and  horizontal  planes  in  practically  the  same  way, 
and  may  be  called  by  the  same  names. 

Changing  Height  of  Tool  Changes  Angle  of  Rake.— As  stated,  it  is 
assumed  in  the  above  that  the  points  of  the  lathe-tools  are  to  be  set 


FIG.  316. 


FIG.  317. 


on  the  level  of  the  lathe-spindle  axis.     We  will  now  investigate  the 
effect  of  deviating  from  this  position.       In  Fig.  316,  let  0  represent 

*  Left  and  right  clearance  means  left  and  right  side  clearance.     The  term 
rake,  sometimes  applied  to  the  angle  of  clearance,  is  not  so  used  in  this  work. 


LATHE-  AND  PLANER-TOOLS  221 

a  cross-section  through  a  cylinder  as  before,  T  the  lathe-tool  set  above 
the  center,  and  T  1,  on  the  opposite  side,  a  similar  lathe-tool  set  below 
the  center.  H  is  a  horizon tal  fine.  It  is  easily  seeti  that  the  "effective" 
front  rake  is  much  greater  in  T^han  in  T  1.  Again,  in  Fig.  317  let  T  2 
be  tipped  *  in  the  tool-post  to  bring  the  point  to  the  center,  and  the 
effective  front  rake  is  again  changed. 

Side  Clearance  Varies  with  Change  in  Diameter  and  Feed. — Joshua 
Rose,  in  "  Modern  Machine-shop  Practice,"  has  called  attention  to  a  fact 
respecting  side  clearance  which  is 
often  overlooked.     In  Fig.  318  let 
T  3  represent  a  section  of  a  tool  the 
same  as  in  Fig.  313,  excepting  that 
it  is  being  traversed  in  the  direction 
of  the  arrow,  at  the  rate  of  I/IQQ  of 
an  inch  for  each  revolution  of  the 
shaft.     In  Fig.  319  let  T  4  have  the  FlG   318  FlG  319 

same   nominal  side  clearance,  and 

let  it  traverse  in  the  same  direction  at  l/^f  per  revolution.  The  effective 
side  clearance  for  the  two  cases  differs  considerably,  as  shown  in  the 
illustrations.  It  differs  also  with  every  change  in  diameter  of  work. 

Clearance  and  Rake  for  Average  Requirements. — From  the  above 
considerations,  and  from  the  fact  that  different  densities  of  metals 
require  different  angles  of  rake,  it  will  appear  that  it  is  impracticable, 
if  not  impossible,  to  maintain  constant  effective  angles  of  rake  and 
clearance.  Nevertheless  it  is  desirable  to  settle  upon  such  angles 
as  will  best  answer  average  requirements,  making  special  tools  for 
special  cases. 

As  to  the  angle  f  for  average  requirements,  Hart,  a  German  authority 
quoted  by  Professor  Robert  Smith  in  his  work  on  cutting-tools,  gives 
51°  as  the  best  cutting  angle  for  wrought  iron  and  cast  iron,  and  3° 
and  4°  respectively  as  the  proper  heel  clearance.  This  gives  36°  and 
35°  for  the  front  rake.  Hart's  experiments  were  made  for  the  purpose  of 
determining  the  best  cutting  angles  for  the  least  power;  but  with  such 
angles  as  he  proposes,  the  tool  would  not  hold  its  edge  well,  and  the 
saving  in  driving  power  would  probably  be  overbalanced  by  the  time 

*  New  tools,  before  much  has  been  ground  from  the  top  face,  are  sometimes 
tipped  in  this  way;  tools  are  also  set  sometimes  above  and  sometimes  slightly 
below  center. 

t  A  valuable  article  on  "Speeds,  Feeds,  and  Angles  of  Metal-cutting  Tools" 
may  be  found  in  "  American  Machinist,"  March  5,  1903,  page  329. 


222  MACHINE-SHOP  TOOLS  AND  METHODS 

dost  in  regrinding  and  readjusting  the  tools.  A  tool  used  for  roughing 
cuts  may  have  about  20°  rake.  For  finishing  cuts,  when  regular  finish- 
ing-tools are  used^  about  8°  should  be  sufficient  for  the  front  rake.  If 
the  corners  are  slightly  rounded  on  such  tools  they  work  fairly  well 
with  little  side  rake.  Tools  which  traverse  to  the  right  or  left  should 
have  about  8°  side  clearance  and  6°  heel  clearance.  This  heel  clearance 
is  right  for  all  the  tools  in  Fig.  288  except  the  threading-tools. 

Rake  and  Clearance  of  the  Standard  Set  of  Tools.  Brass  Tools 
without  Rake. — Referring  to  Fig.  288,  all  these  tools  have  heel  clear- 
ance and  either  right  or  left  clearance.  No.  1  has  left  rake;  Nos.  2 
and  3,  right  rake;  No.  4,  front  and  right  rake;  No.  5,  front  and  left 
rake;  Nos.  6  and  10,  front  rake.  No.  7  should  have  front  rake  except 
when  used  on  brass,  and  No.  11  should  have  both  front  and  right  rake 
except  for  brass.  Thread-tools  are  made  without  any  rake,  but  when 
used  on  other  metal  than  brass  the  thread-tool  could  have  front  rake 
for  the  roughing  cuts.  The  reason  for  not  giving  rake  to  tools  used 
on  brass  is  that  when  made  with  rake  they  tend  to  gouge  into  the  metal. 
Some  mechanics,  however,  use  tools  having  rake  on  brass.  In  this 
case  the  gib-screws  of  the  carriage  should  be  snugly  adjusted. 

For  light  cuts,  in  which  some  machinists  prefer  to  traverse  the  car- 
riage both  right  and  left  without  change  of  tool,  the  tools  for  longi- 
tudinal cutting,  such  as  roughing-tools,  diamond-point  tools,  etc.,  may 
have  front  rake  only.  If  made  with  right  or  left  rake,  they  work  at  a 
disadvantage  in  traversing  in  right  and  left  directions  respectively. 
For  heavy  work  these  tools  should  be  made  with  both  front  and  right 
rake  when  they  are  to  traverse  to  the  left,  and  with  left  and  front  rake 
when  they  are  to  traverse  to  the  right.  Most  machinists  make  the  tools 
in  the  latter  forms,  even  for  light  work. 

Rake  and  Clearance  for  Exceptional  Cases.  Less  Clearance  for 
Planer-tools.  —  For  exceptionally  hard  metals,  such  as  chilled  iron, 
the  clearance  should  be  reduced  to  a  minimum,  and  the  angle  of 
rake  should  also  be  very  much  less  than  above  proposed.  The  keen 
edge  ordinarily  used  on  wrought  iron  and  machine-steel  would  be  very 
quickly  destroyed  cutting  chilled  iron.  The  cutting-off  tool  and  other 
tools  which  cut  in  front  only,  and  do  not  traverse  lengthwise  the  work, 
require  very  little  side  clearance.  From  2  to  3  degrees  is  sufficient  for 
these  tools. 

All  that  has  been  said  respecting  the  rake  of  lathe-tools  will  apply 
equally  well  to  planer-tools.  The  clearance,  however,  of  planer-tools 
may  be  less.  From  3  to  6  degrees  will  be  about  right  for  both  side 


LATHE-  AND  PLANER-TOOLS  223 

and  heel  clearance.  One  reason  why  planer-tools  require  less  clearance 
is  because  they  are  not,  or  at  least  should  not  be,  fed  to  the  work  during 
the  time  that  the  tool  is  cutting.  The  feeding  should  be  done  at  either 
end  of  the  stroke.  If_the  difference  in  the  case  of  the  planer  is  not 
understood,  read  again  the  discussion  respecting  Figs.  318  and  319. 

Lubricants  Used  in  Turning,  Drilling,  etc. — All  operations  on  cast 
iron,  such  as  turning,  drilling,  reaming,  etc.,  are  usually  performed  dry, 
but  some  mechanics  tap  cast  iron  with  oil,  and  others  advocate  the  use 
of  water  in  turning  cast  iron.  All  the  above  operations  on  wrought  iron 
and  steel  may  be  performed  in  connection  with  oil  or  some  cheaper  mix- 
ture, except  that  lard-oil  should  be  used  in  reaming.  To  avoid  the 
dirty  condition  of  the  lathe  which  results  from  the  use  of  oil  or  soda- 
water  we  frequently  turn  wrought  iron  and  steel  dry.  All  operations 
on  brass  may  be  performed  dry,  except  that  some  machinists  prefer  to 
use  oil  in  tapping  brass.  Copper  should  be  machined  dry,  except  that 
in  reaming  lard-oil  should  be  used.  In  turning,  drilling,  etc.,  in  Babbitt 
metal  no  lubricant  is  required.  In  drilling  glass  use  turpentine  or 
kerosene  oil. 

A  cheap  compound  may  be  purchased  for  use  in  lubricating  and 
cooling  cutting-tools.  The  air  blast  is  sometimes  used  for  the  latter 
purpose. 


CHAPTER  XIV 
LATHE-CENTERS,  WORK-CENTERS,  ETC. 

Ideal  Condition  for  Lathe -centers. — The  proper  care  of  lathe-centers 
and  work-centers  is  of  such  importance  that  it  seems  well  to  emphasize 
it  by  devoting  a  chapter  to  the  subject.  In  grinding  work  between 
centers  on  the  universal  grinder,  both  centers  are  stationary,  while  the 
work  revolves.  The  centers  cannot,  under  these  conditions,  affect 
the  concentricity  of  the  work.  This  is  the  principle  upon  which  lathes 
doubtless  would  be  constructed  if  there  were  not  serious  practical  dif- 
ficulties in  the  way.  Nevertheless,  as  lathes  are  now  constructed,  the 
center  in  the  main  spindle  revolves,  and  any  eccentricity  that  there 
may  be  in  this  center  is  transferred  to  the  work.  The  prevention  of 
this  eccentricity  requires  extreme  care,  as  will  be  explained  below. 

Taper  of  Lathe -centers ;  Angle  of  Point,  etc. — In  the  wood-turning 
lathe  there  is  one  spur-center  and  one  center  with  cup  point,  the  former 
being  of  such  a  shape  as  to  cut  into  and  drive  the  work.  In  the  metal- 
turning  lathe  both  centers  have  conical  points,  as  in  Fig.  320,  and  the 


FIG.  320. 

work  is  driven  by  the  lathe-dog.  There  is  no  standard  for  the  taper  of 
the  lathe-centers,  but  they  are  seldom  made  more  than  5/8"  nor  less 
than  l/2*  taper  per  foot.  The  Morse  taper,  given  elsewhere  in  this  book, 
is  approximately  5/s"  per  foot,  and  this  taper  is  sometimes  used  on  lathe- 
centers. 

There  is  a  tendency  toward  the  adoption  of  standards  for  all  regular 
machine  details,  and  doubtless  manufacturers  will  at  some  future  day 
adopt  a  standard  for  lathe-centers.  In  anticipation  of  this  time  Oscar 
Beale  has  proposed  a  system  in  which  the  dimensions  of  a  taper  are  in- 
dicated by  its  mimber.  In  Mr.  Beale  Js  system  the  number  designating 

224 


LATHE-CENTERS,  WORK-CENTERS,  ETC.  225 

a  certain  size  of  taper  expresses  the  number  of  tenths  of  an  inch  at  the 
small  end  of  the  taper,  the  number  of  eighths  at  the  large  end,  and  the 
number  of  halves  of  an  inch  of  its  .length.  Thus  number  10  taper  would 
be  I"  at  small  end,  !1/4/-at  the  large  end,  and  5"  in  length. 

Respecting  the  conical  point  of  the  center  there  is  less  variation 
in  practice;  nearly  all  machinists  use  60°  as  the  standard  angle  of  centers 
for  small  work,  though  some  prefer  a  greater  angle  for  heavy  work.  It 
has  been  demonstrated,  however,  that  60°  makes  a  center  sufficiently 
strong  for  the  heaviest  work,  and  this  should  be  adopted  as  the  standard. 
The  standard  60°  gage  for  testing  the  point  of  a  lathe-center  can  be  bought 
from  machinery  supply  stores. 

It  is  very  Important  to  keep  the  Centers  True,  and  previous  to  the 
introduction  of  center-grinding  machines  the  best  mechanics  would  leave 
the  live  center  (the  center  which  revolves)  soft,  and  turn  it  and  re-turn 
it  as  often  as  necessary.  The  difficulty  in  this  method  is  that  in  heavy 
work  the  center  may,  without  the  knowledge  of  the  workman,  be  strained 
slightly  out  of  true,  and  this  would  cause  eccentricity  in  the  work  to  be 
turned.  A  better  plan  is  to  harden  both  centers,  and  keep  them  in  good 
condition  by  grinding  them  as  often  as  necessary.  The  machines  designed 
for  this  purpose  are  usually  fastened  in  the  tool-post  like  an  ordinary  lathe- 
tool,  and  the  emery-wheel  is  generally  driven  either  by  a  belt  or  by 
frictional  contact  of  a  small  pulley  with  the  cone  pulley  or  face-plate  of 
the  lathe.  One  of  the  most  convenient  machines  for  this  purpose  is 
so  designed  that  it  may  be  adjusted  for  correct  angle  by  merely  supporting 
it  between  the  lathe-centers  and  tightening  the  tool-post  in  the  usual 
manner.  This  machine  is  shown  in  Fig.  321  in  position  on  the  centers  as 
indicated.  The  adjustment  in  the  tool-post  should  be  such  that  this 
alinement  of  the  grinder  will  not  be  disturbed  when  the  tail-spindle  of 
the  lathe  is  withdrawn.  When  the  grinder  is  thus  adjusted,  the  lathe 
tail-stock  is  moved  out  of  the  way,  the  emery-wheel  advanced  to  the 
left  by  the  knob  E,  and  the  wheel  brought  into  contact  with  the  center 
by  the  combined  movement  of  cross-slide  and  carriage.  The  rubber 
pulley  D  is  next  pressed  against  the  revolving  cone  pulley,  which  should 
run  backwards  at  its  highest  speed,  when  the  grinding  may  be  commenced. 
For  each  traverse  of  the  emery-wheel  over  the  surface  of  the  center 
(which  traverse  is  effected  by  the  knob  E)  the  cross-slide  of  the  lathe 
is  fed  inward  a  small  fraction,  this  process  being  repeated  until  the  grind- 
ing is  done. 

The  small  emery-wheel  should  be  " touched  up"  with  a  diamond  as 
often  as  it  becomes  glazed. 


226 


MACHINE-SHOP  TOOLS  AND  METHODS 


A  center-grinder  has  recently  been  introduced,  which  is  so  constructed 
that  it  may  be  driven  by  merely  making  connection  with  an  electric 
drop-cord. 


To  lessen  the  work  of  grinding  the  centers,  they  are  frequently  turned 
with  a  shoulder  as  in  Fig.  322. 

When  the  point  of  the  center  breaks  it  must  be  annealed  and  re-turned, 
as  the  grinder  is  not  intended  for  removing  any  considerable  amount 


LATHE-CENTERS,  WORK-CENTERS,  ETC.  227 

of  metal.     Before  inserting  the  center  in  the  spindle,  any  grit  that  may 
have  adhered  to  the  body  of  the  .center  should  be  carefully  removed. 


FIG.  322. 

Further  Precautions  as  to  Centers. — It  is  impossible  to  exaggerate 
the  importance  of  keeping  the  centers  true.  If  a  shaft  be  turned  half 
its  length  with  the  live  center  eccentric,  and  then  reversed  and  the 
other  end  turned,  the  two  ends  of  the  shaft  will  be  eccentric  with  each 
other.  The  smallest  speck  of  grit  between  the  body  of  the  center  and 
the  hole  in  the  spindle,  or  between  the  point  of  the  center  and  the  center 
in  the  work,  mil  cause  an  appreciable  eccentricity  in  the  work.  To  avoid 
this  eccentricity,  first,  the  centers  should  be  carefully  wiped;  second, 
the  spindle-socket  should  be  carefully  cleaned.  This  is  best  effected 
by  wrapping  clean,  dry  waste  around  a  stick  and  swabbing  the  socket 
while  the  spindle  is  in  motion.  Third,  the  center  should  have  a  witness- 
line  matching  a  similar  line  on  the  end  of  the  spindle,  and  these  lines 
should  correspond  when  the  center  is  in  place.  Fourth,  the  point  of 
the  lathe-center  and  the  center  in  the  work  should  fit  and  be  free  from 
dirt.  As  a  further  precaution  the  centers  when  removed  from  the 
lathe-spindle  should  be  placed  in  wooden  brackets  fastened  to  the  lathe, 
or  otherwise  kept  from  contact  with  other  tools;  also  clean  waste  should  be 
placed  in  the  spindle-socket  when  the  center  is  removed.  If  mixed 
promiscuously  with  other  tools,  the  centers  will  be  marred  or  scratched, 
which  will  cause  eccentricity  in  the  work. 

A  slight  error  in  the  tail-center  cannot  cause  eccentricity  in  the 
work,  but  it  may  affect  the  parallelism  of  the  work ;  and  a  speck  of  grit 
or  a  scratch  might  cause  looseness  of  the  center,  which  would  cause  chat- 
tering. Both  of  these  difficulties  are  to  be  avoided  by  keeping  this 
center,  also,  free  from  dirt  and  scratches.  As  another  safeguard  against 
tapering  work,  especially  in  old  lathes,  it  is  well  to  have  witness-marks 
for  the  tail-center  also. 

Square  Centers. — In  metal-turning  lathes  (except  when  a  chuck 
is  used)  the  lathe-dog  is  commonly  used  to  drive  the  work.  This  is 
almost  an  invariable  rule;  but  there  is  one  exception:  On  very  small 
brasswork,  especially  when  it  is  desirable  to  turn  the  full  length  of  the 
work  without  reversing  it  in  the  lathe,  a  square  center  may  be  used. 


228 


MACHINE-SHOP  TOOLS  AND   METHODS 


This  center  is  shown  in  Fig.  323.     The  center  in  the  work  must  obviously 
be  made  with  a  punch  having  a  point  of  a  shape  corresponding  to  the 


FIG.  323. 

shape  of  the  lathe-center.  On  diameters  greater  than,  say,  about  3//' 
the  resistance  of  the  cut  will  generally  be  greater  than  the  driving  power 
of  the  square  work-center;  for  this  reason  the  square  center  cannot  be 
used  on  large  diameters. 

The  Female  Center  has  its  outer  end  shaped  the  reverse  of  the  conical- 
point  center,  as  illustrated  in  Fig.  324.     This  form  of  center  may  be 


FIG.  324. 

used  on  small  work,  in  which  case  the  end  of  the  work  next  to  the  head 
spindle  of  the  lathe  requires  no  work-center.  If  the  center  in  the 
tail-spindle  be  made  of  the  same  form,  that  end  of  the  work  could  also 
be  used  without  a  work-center.  The  difficulty  in  this  case,  however, 
-would  be  that  the  extreme  ends  of  the  work  could  not  be  machined. 
The  female  center  is  seldom  used,  but  when  it  is  used  it  has  the 
advantage  of  truing  the  work  automatically. 

Pipe -centers.  —  It  is  sometimes  necessary  to  thread  or  otherwise 
machine  common  pipe.  When  the  ordinary  lathe-centers  are  large  enough, 
such  work  may  be  machined  on  these  centers;  but  for  the  larger  sizes 
of  pipe  it  is  necessary  to  have  special  centers.  These  pipe-centers  are 
best  made  in  two  parts,  as  illustrated  in  Fig.  325.  The  arbor  part  of 
the  metal  fits  the  lathe-spindle  in  the  usual  manner.  The  conical  end 
of  the  center  in  the  tail-spindle  is  detachable,  and  revolves  upon  the 
arbor.  These  centers  may  be  made  to  take  pipes  as  large  as  6"  diame- 
ter, or  larger. 

Proportions  of  Centers.  Tools  for  and  Methods  of  Centering  Work. 
In  centering  a  shaft  or  other  similar  detail,  it  is  first  necessary  to  locate 


LATHE-CENTERS,  WORK-CENTERS,  ETC. 


229 


the  position  for  the  center.     This  may  be  done  by  means  of  the  center- 
square  or  compass-caliper  for  ttye  "larger  shafts,  and  a  bell-punch  for  the 


FIG.  325 

smaller  sizes,  as  explained  in  a  subsequent  paragraph.  In  using  the 
latter  the  center  is  located  and  indented  at  the  same  time.  In  using 
the  center-square  or  compass-caliper  we  merely  mark  a  position  for  the 
center,  and  then  indent  this  position  with  the  center-punch  and  hammer. 
Having  located  and  indented  the  center,  we  next  drill  and  ream  it. 
The  depth  of  the  drilled  center  should  be  such  that  the  extreme  point 
of  the  lathe-center  shall  clear  the  bottom  of  the  hole  Vie"  or  more. 
The  diameter  of  the  drill  may  be  Vie"  for  1/4r  to  Vs-mch  shafts,  3/32" 
above  1/2-  to  !1/4-inch,  and  Vs"  for  sizes  larger  than  lV4-hich.  The 
countersink  should  be  60°  angle,  and  the  largest  diameter  of  the 
countersink  in  the  work  should  equal  the  diameter  of  the  shaft  X3/ie 
for  sizes  above  l/2"  in  diameter.  For  shafts  1/2"  and  less  it  will 
be  sufficient  to  just  ream  away  the  sharp  corners  of  the  drilled  center. 
Shafts  and  other  work  turned  on  centers  should  generally  be  faced  on 
the  ends  before  the  longitudinal  turning  is  started,  and  the  drilling 
and  reaming  should  be  enough  deeper  than  the  above  proportions  to 
allow  for  the  facing. 

The  Center-square,  referred  to  in  the  preceding  paragraph,  is  so 
constructed  that  if  pressed  against  a  shaft,  as  in  Fig.  326,  one  edge  of 
its  blade  will  pass  through  the  center  of  the  shaft  end.  The  center  may 
be  thus  located  by  marking  two  intersectiong  lines  with  the  scriber. 

The  Use  of  the  Bell  Center-punch  is  illustrated  in  Fig.  327.  The 
punch  should  be  held  as  nearly  true  with  the  axis  of  the  shaft  as  may 
be  readily  determined  with  the  eye.  If  there  are  lumps  or  irregularities 


230 


MACHINE-SHOP  TOOLS  AND  METHODS 


on  the  edge  where  the  instrument  touches,  these  should  be  removed 
with  a  file,  or  the  center  would  not  be  accurately  located.     There  would 


FIG.  326. 


FIG.  327. 


FIG.  328. 


be  an  error,  also,  in  the  location  of  the  center  in  case  the  end  of  the 
shaft  were  much  out  of  square  with  its  axis. 

The  Use  of  the  Hermaphrodite  Caliper  for  centering  a  shaft  is  shown 
in  Fig.  328.  For  centering  set  the  calipers  to  the  radius  of  the  shaft,  and 
with  the  caliper  leg  against  the  periphery  of  the  shaft  describe  an  arc 
with  the  other  leg.  Describe  two  other  arcs  in  a  similar  way.  The 
center  will  thus  be  indicated. 

Center-drills  and  Center-reamers.  Centering-machines. — An  ordi- 
nary twist-drill  may  be  used  for  drilling  centers,  and  they  may  be  reamed 


FIG.  329. 


FIG.  330. 


with  a  reamer  like  that  shown  in  Fig.  329.  Some  prefer  a  drill  and 
reamer  combined,  as  shown  in  Fig.  330.  The  above  tools  may  be  used 
for  centering  work  in  a  sensitive  drill  similar  to  Fig.  116,  or  they  may 
be  used  in  a  lathe,  preferably  a  speed-l&ihe.  In  either  case  the  drill 
generally  revolves. 


LATHE-CENTERS,  WORK-CENTERS,  ETC. 


231 


When  the  centering  is  done  in  the  lathe  the  work  is  supported  at 
one  end  on  the  tail-center,  and,  if  small,  the  work  is  held  by  the  hand  on 
the  opposite  end.  More  accurate,  drilling  will  result  if  the  work  be 
given  a  half-revolution  back  and  forth  several  times  during  the  drilling. 

Heavy  work  should  be  securely  supported  at  both  ends;  and  when 
any  cylindrical  work,  heavy  or  light,  is  to  be  centered  with  special  accu- 
racy, it  may  be  driven  by  a  chuck  and  guided  on  the  right-hand  end  by 


FIG.  331. 

a  steady  rest,  as  will  be  explained  in  another  chapter.    In  such  cases 
the  work  revolves. 

Fig.  331  shows  a  machine  designed  especially  for  centering.  In 
centering  work  in  this  machine  it  is  unnecessary  to  indent  the  center. 
The  work  is  gripped  in  the  universal  chuck  and  held  central  with  the 
revolving  drill.  The  latter  is  supported  in  a  socket  with  so  little  pro- 


232 


MACHINE-SHOP  TOOLS  AND  METHODS 


jection  that  there  is  but  little  chance  for  deflection.    These  drills  and 
sockets  are  shown  in  Fig.  332.     The  machine  is  driven  by  the  counter- 


FIG.  332. 


shaft  shown,  and  the  drill  is  fed  by  the  handle  at  the  right  end  of  the 
head-stock. 


CHAPTER  XV 
METHODS  OF  DRIVING  WORK  IN  THE  LATHE.     DOGS  AND  CHUCKS 

Driving  Work  by  a  Common  Lathe -dog. — When  work  of  the  character 
of  a  shaft  is  to  be  turned  on  centers  it  is  in  most  cases  driven  by  a  lathe- 
dog.  To  drive  a  shaft,  for  instance,  the  dog  is  placed  on  the  end  of  the 
shaft  and  its  set-screw  tightened.  It  is  then  placed  on  the  lathe-centers 
in  such  a  manner  that  the  tail  of  the  dog  engages  with  a  slot  in  the  lathe 
face-plate,  as  shown  in  Fig.  333,  or  with  a  stud  projecting  from  the  face- 


FIG.  333. 

plate.  In  both  of  these  methods  there  is  a  slight  tendency  to  cramp 
and  deflect  the  work,  but  with  ordinary  care  either  of  the  methods  will 
answer  passably  well. 

The  tail  of  the  dog  should  fit  freely  between  the  sides  of  the  slot, 
and  it  must  have  clearance  in  the  bottom  of  the  slot.  The  latter  is  of 
special  importance  in  turning  work  with  the  tail-stock  set  over,  which 
is  one  method  of  turning  tapering  work.  In  using  the  lathe-dog  for 
this  work  the  tail  of  the  dog  moves  back  and  forth  in  the  slot,  and  it 
is,  therefore,  necessary  to  turn  the  lathe  around  slowly  and  see  that 
the  dog  clears  the  slot  throughout  one  revolution.  Otherwise  the  work 
may  be  forced  off  the  lathe  centers. 

Using  a  Double-end  Dog. — To  overcome  the  cramping  tendency 
the  double-end  dog  shown  in  Fig.  334  is  sometimes  used.  Unless  special 
care  is  exercised  to  see  that  this  dog  has  contact  at  both  ends  its  value 

233 


234 


MACHINE-SHOP   TOOLS  AND  METHODS 


will  be  neutralized,  and  it  will,  in  effect,  become  a  single-end  dog.  To 
insure  accurate  contact  it  is  well  to  have  screw-adjustment  in  one  of 
the  drivers  for  such  a  dog,  as  illustrated  in  Fig.  335. 


FIG.  334. 


FIG.  335. 


FIG.  336. 


Protecting  Finished  Work. — When  the  lathe-dog  is  to  be  used  on 
finished  work  the  latter  should  be  protected  by  placing  a  bit  of  sheet 
brass  between  the  set-screw  and  the  work.  As  a  further  protection, 
in  particular  cases,  a  sleeve  made  of  sheet  brass  and  fitting  nearly  around 
the  work  may  be  used. 

Dog  for  Taper  Work. — Fig.  336  shows  a  clamp  dog  which  grips  the 
work  by  two  screws,  neither  of  which  touches  the  work.  This  dog 
is  made  with  and  without  the  swivel  joint,  but  when  made  as  shown 
it  will  grip  tapering  work  squarely  and  hold  well.  With  or  without 
the  swivel  it  will  drive  "straight"  work.  It  will  mar  the  work  much 
less  than  the  dog  first  described,  but  it  should,  nevertheless,  be  used 
in  connection  with  the  brass  sleeve  for  polished  work. 

Dogs  for  Threaded  Work. — When  threaded  work  is  to  be  turned 
on  centers  a  special  dog  made  like  Fig.  337  *  is  desirable.  This  dog 
is  split  on  one  side,  and  by  means  of  the  screw  S  it  may  be  tightened  to 
grip  the  bushing  B,  which  is  also  split.  The  bushing  is  threaded  inter- 
nally to  fit  one  size  of  screw,  a  different  bushing  being  required  for 
each  size  of  screw.  Tightening  the  screw  S  closes  the  bushing  and 
grips  the  screw  which  is  to  be  driven. 


*Cut  taken  from  an  article  by  "Cherry  Red"  in  "American  Machinist,' 
27,  page  153. 


vol 


METHODS  OF  DRIVING  WORK  IN  THE  LATHE 


235 


Another  method  consists  in  using  the  ordinary  dog  in  connection  with 
a  nut  which  fits  the  thread.  .This  nut  is  sawed  through  on  one  side. 
Tightening  the  set  screw  of  the  .dog  on  the  nut  causes  the  latter  to  grip 
the  thread  of  the  screw:  - 

If  two  nuts  be  used,  one  being  tightly  jammed  against  the  other, 
and  the  dog  tightened  on  the  outer  nut,  neither  of  the  nuts  will  need 
to  be  split. 

Some  workmen  try  to  protect  the  thread  by  merely  using  a  brass 
sleeve  under  the  set-screw  of  the  common  dog,  the  same  as  when  turning 


FIG.  337. 


plain  work.  This  is  unsatisfactory,  except,  perhaps,  with  square  threads, 
but  even  here  it  is  not  good  practice.  Inasmuch  as  a  common  nut  sawed 
through  on  one  side  costs  but  a  trifle,  it  is  generally  inexcusable  to  use 
the  common  dog  and  brass  sleeve  on  either  a  V  thread  or  U.  S.  standard 
thread. 

The  Bolt-dog. — Square  sections,  hexagonal  sections,  etc.,  may  be 
driven  by  an  ordinary  lathe-dog,  but  when  there  is  much  of  this  work 
a  special  dog  bolted  to  the  face-plate  as  shown  in  Fig.  338  is  preferable. 
This  dog  will  drive  either  square  or  hexagonal  stock,  or,  indeed,  any 
section  which  has  two  parallel  flat  sides.  It  saves  time  in  machining 
bolts  when  these  are  to  be  made  by  the  slow  engine-lathe  process. 


236 


MACHINE-SHOP  TOOLS  AND  METHODS 


Driving  Work  on  Centers  without  a  Dog. — In  the  chapter  on  lathe 
centers  the  method  of  driving  work  by  a  square  center  has  already 
been  mentioned.  A  more  accurate  method  is  that  illustrated  in  Fig.  339. 


FIG.  338. 


-DRIVER 


FIG.  339. 


This  figure  shows  a  conical  center  with  a  groove  milled  in  one  side  to  receive 
a  driver  which  is  held  by  a  set-screw.  The  work  has  a  notch  milled  in 
its  end  to  engage  with  the  driver. 


CHUCKS 


Definition  and  Classification. — A  chuck  is  a  kind  of  vise  designed 
to  screw  on  the  lathe-spindle  and  grip  work,  causing  it  to  revolve  with 
the  spindle.  Chucks  are  made  in  the  independent  type,  in  which  the 


METHODS   OF  DRIVING  WORK  IN  THE  LATHE 


237 


gripping  jaws  are  moved  separately;  in  the  universal  type,  in  which  all 
the  jaws  are  moved  simultaneously;  and  in  the  combination  design,  in 
which  the  jaws  may  be  moveo^  separately  or  together. 

Independent  Chucfcs. — These  chucks  are  made  for  general  work 
with  either  three  or  four  jaws,  which  are  usually  reversible.  For  special 
work  they  are  sometimes  made  with  two  jaws,  and  for  very  large  work 
with  more  than  four  jaws.  Fig.  340  shows  a  perspective  view  of  a  four- 


jaw  independent  chuck.  Each  jaw  has  three  shoulders  or  "bites,", 
besides  the  outer  bite.  The  jaws  are  moved  by  a  key  or  socket  wrench, 
which  fits  the  square  ends  of  the  screws  seen  just  under  the  jaws,  being 
guided  in  accurately  fitting  radial  ways.  When  the  jaws  are  placed 
as  shown  in  the  illustration,  three  different  large  diameters  may  be 


FIG.  341. 

gripped  on  the  outside  and  one  on  the  inside.  The  jaws  will,  of  course, 
close  up  for  smaller  diameters.  When  reversed  the  jaws  have  one 
outside  bite  and  three  internal  bites. 

Fig.  341  shows  a  sectional  view  with  one  jaw  and  one  screw  removed. 


238 


MACHINE-SHOP  TOOLS  AND  METHODS 


To  remove  or  reverse  a  jaw,  it  is  necessary  only  to  revolve  the  screw 
until  the  jaw  is  moved  radially  beyond  the  screw-thread;  it  may  then 
be  withdrawn.  On  sliding  it  into  the  ways  again,  with  or  without 
reversing,  and  turning  the  screw  in  the  right  direction  the  threads  of 
the  screw  will  again  engage  those  on  the  under  side  of  the  jaw. 

Machining  the  Back  Plate  for  a  Chuck. — A  chuck  does  not  screw 
directly  on  the  lathe-spindle;  but  a  plate  which  screws  on  the  spindle, 
is  made  to  fit  the  recess  on  the  back  of  the  chuck.  In  Fig.  342  is  shown 


FIG.  342. 


FIG.  343. 


FIG.  344. 


such  a  plate  screwed  on  a  lathe-spindle,  the  chuck  being  bolted  to  it 
in  the  usual  manner.  This  figure  shows  also  a  similar  plate  Z), 
gripped  in  the  chuck,  ready  to  be  bored  and  threaded.  This  work  is 
usually  done  by  the  purchaser,  rather  than  the  manufacturer  of  the 
chuck.  The  plate  should  be  bored  about  .01"  larger  than  the  root 
diameter  of  the  thread  on  lathe-spindle.  It  should  also  be  counter- 
bored  as  at  c  to  fit  a  blank  place  about  3/8"  long  next  to  the  thrust- 
collar  on  the  lathe-spindle.  The  collar  referred  to  is  lettered  C  1  in 
the  illustration.  With  an  inside  thread  tool  of  the  proper  shape,  and 
a  wire  rod  filed  *  to  a  length  equal  to  the  outside  diameter  of  the  lathe- 
spindle  thread,  and  tapered  at  the  point  as  shown  in  Fig.  343,  the 
thread  may  be  cut  and  measured.  The  rod  can  be  measured  by  com- 
mon calipers,  which  should  be  set  to  the  diameter  of  the  thread,  measured 


*  If  filed  too  short  the  rod  may  be  stretched  by  peenmg  it  near  the  middle 
with  a  hammer  while  held  over  a  block  of  metal. 


METHODS  OF  DRIVING  WORK  IN  THE  LATHE  239 

on  an  angle  as  shown  in  Fig.  344.  The  rod  need  not  be  made  to  fit 
the  sides  of  the  thread,  but  should  touch  on  ends  only.  When  the 
thread  has  been  cut  deep  enough  to  admit  of  the  rod  or  gage  being 
screwed  through,  or  nearly  through,  the  chuck  and  plate  together  should 
be  removed  from  the  spindle  and  tried  on  the  spindle  for  which  the 
plate  is  being  made.  Before  trying  it,  however,  the  chips  should  be 
cleaned  out  of  the  thread  (preferably  by  a  small  hand-bellows),  and 
the  spindle  thread  should  be  wiped  with  clean  waste  which  has  been 
moistened  with  a  few  drops  of  oil.  For  want  of  oil  the  writer  has 
known  a  chuck-plate  to  seize  the  spindle  so  firmly  as  to  necessitate 
splitting  the  plate  in  two  parts  before  it  could  be  removed.  No  lubri- 
cant is  needed  in  cutting  thread  with  a  single  point  tool  in  cast  iron. 
In  the  case  of  the  chuck  casting,  oil  will  cause  the  fine  chips  to  stick  in 
the  thread,  and  will  thus  do  harm  rather  than  good. 

If  the  casting  will  not  screw  on  the  spindle  it  may  be  threaded  a 
little  larger  and  tried  again.  Had  the  plate  been  removed  from  the 
chuck  it  would  have  been  difficult  to  grip  it  concentrically  again.  Before 
removing  the  plate  the  hub  H  and  face  F  may  be  machined.  When 
this  is  done  the  plate  should  be  removed  and  screwed  on  the  spindle 
of  its  lathe,  with  large  face  out.  This  face  may  now  be  machined,  and 
the  edge  or  periphery  E  may  be  turned  so  as  to  fit  (not  too  tightly  but 
without  shake)  the  recess  in  the  back  of  the  chuck.  The  plate  should  next 
be  placed  in  the  recess  and  marked  off  with  a  scriber,  and  then  drilled 
for  a  free  fit  of  the  bolts  accompanying  the  chuck.  If  the  bolt-holes  in 
the  chuck  are  not  drilled  entirely  through,  smear  the  face  of  the  plate 
with  red  lead  mixed  with  oil  to  the  consistency  of  paste,  and  on  pound- 
ing the  plate  into  the  recess,  the  holes  will  be  marked. 

The  Universal  Chuck. — A  typical  universal  chuck  is  shown  in  Fig. 
345.  The  jaws  are  operated  by  a  socket-wrench  the  same  as  the  chuck 
previously  described,  but  when  one  screw  is  turned  the  other  screws 
are  forced  to  turn  with  it  by  mechanism  which  will  now  be  described. 
In  Fig.  346  is  shown  a  bevel-gear  or,  as  the  makers  call  it,  a  "  circular 
rack."  Engaging  with  this  gear  are  three  pinions  (or  as  many  as  there 
are  jaws)  made  integral  with  the  screws  which  move  the  jaws,  as  shown 
in  Fig.  347.  The  circular  rack  turns  freely  in  the  casing  of  the  chuck, 
which  is  divided  in  two  parts,  as  can  be  seen  in  Fig.  345,  and  held 
together  by  bolts.  It  is  obvious  that  with  jaw-screws  of  the  same 
pitch,  all  the  jaws  must  move  the  same  distance.  It  is  equally  cleai 
from  the  construction,  that  the  jaws  must  move  simultaneously. 

This   chuck  is  made  also  with  modifications  which  admit  of  dis- 


240 


MACHINE-SHOP  TOOLS  AND  METHODS 


engaging  and  reengaging  the  circular  rack  and  pinions,  thus  converting 
it  into  a  combination  chuck.     Fig.  348  shows  the  combination  chuck  with 


FIG.  345. 


FIG.  346. 


back  plate  removed.  It  is  changed  from  universal  to  independent  and 
vice  versa,  by  moving  the  steel  shoes  (which  are  attached  to  the 
thumb-nuts)  backward  or  forward  around  the  inclined  plane  on  the 
loose  ring. 


FIG.  347. 


Combination  Chuck  Operated  by  a  Scroll.— The  form  of  gearing 
known  as  the  scroll  is  much  used  in  connection  with  chucks,  and 
it  is  employed  very  successfully  in  the  chuck  shown  in  Fig.  349. 


METHODS  OF  DRIVING  WORK  IN   THE  LATHE 


241 


The  scroll  is  shown  in  section  at  DD  and  in  full  in  Fig.  350.  It  fits 
closely  in  the  chuck  as  shown;"  being  held  in  place  by  the  threaded 
collar  E.  The  sliding-box  C  hafe  teeth  which  engage  the  scroll  teeth, 
so  that  when  the  scrollls  turned  the  sliding-boxes  move  radially.  The 
screws  B  are  carried  by  the  sliding-boxes,  as  are  also  the  jaws  A,  whose 


C          B 


FIG.  349. 


FIG.  350. 


threads  engage  with  the  threads  of  the  screws.  We  thus  have  a  uni- 
versal chuck.  But  the  screws  may  be  operated  separately,  and  inde- 
pendently with  respect  to  the  scroll,  and  this  feature  makes  an  inde- 
pendent chuck.  The  combination  of  these  two  features,  as  previously 
stated,  constitutes  the  combination  chuck. 

Neither  the  universal  chuck,  nor  the  combination  when  used  as  a 
universal  chuck,  is  reliable,  when  old,  for  work  requiring  a  high  degree 
of  accuracy.  These  chucks,  nevertheless,  are  very  satisfactory  for  a 
large  portion  of  the  work  for  which  they  are  designed. 

Chucks  with  Slip  jaws. — For  some  lines  of  work  a  special  form  of 
chuck  is  made  with  the  jaws  in  two  parts.  In  these  chucks  the  "bites" 
or  slip  jaws  may  be  easily  removed,  and  replaced  by  other  slip  jaws 
adapted  to  grip  special  shapes.  Fig.  351  shows  a  two-jaw  independent 
chuck  of  this  character.  The  slipjaws  are  dovetailed  into  the  main 
jaws,  and  are  held  by  pins. 

This  chuck  is  made  also  with  one  screw  having  right  and  left  threads, 
in  which  case  it  is  a  universal  chuck. 


242 


MACHINE-SHOP  TOOLS  AND  METHODS 


Valve -chucks. — The  chuck  illustrated  in  Fig.  352  is  designed  espe- 
cially for  valves,  faucets,  fittings,  etc.,  and  a  valve  is  shown  between  the 
jaws.  One  of  its  faces  having  been  machined,  the  valve  may  be  turned 
on  its  axis  90°,  or  any  angle,  without  being  removed  from  the  chuck. 
The  angle  is  indicated  by  an  index  plate. 


FIG.  351. 

Face-plate    Jaws. — Large  work  is  sometimes    held  by  chuck- jaws 
secured  to  the  ordinary  face-plate.      These  jaws  are  bolted  to  the  large 


FIG.  352. 

face-plate  of  a  lathe,  but  when  not  needed  they  may  be  detached  without 
removing  the  plate. 


METHODS   OF  DRIVING  WORK  IN  THE  LATHE 


243 


"  Home-made  "  Chucks. — Chuck-making  is  a  specialty,  and  the  chucks 
described  in  the  preceding  pa^es  are  sold  by  factories  having  special 
equipment  cheaper  than  they  caji  be  made  in  the  ordinary  machine- 
shop.  Nevertheless  a  great  variety  of  simple  chucking  devices  which 
require  no  special  tools  are  made 
in  the  shops  in  which  they  are 
used.  Fig.  353,  which  was  de- 
scribed by  H.  A.  Houghton  in 
"  American  Machinist/'  vol.  27, 
page  83,  shows  a  chuck  used  for 
packing  rings  and  other  similar 
work.  The  main  part  A,  which 
screws  on  the  lathe-spindle,  has  a 
number  of  cylindrical  steps  to 
take  different  diameters.  When 
turning  the  outside  diameter  of  a 
ring  the  latter  is  held  by  a  clamp 
and  stud,  as  shown  at  B. 

Fig.  354  *  shows  an  expansion- 
chuck.      The    part   a   screws  on 

.    ,,         .     ,,  .  FIG.  353. 

the  lathe-spindle  as  in  the  previous 

case,   and   the  clamp  c  forces  the  split  bushing  against  the  taper  seat. 


FIG.  354. 


Being  split  the  bushing  expands,  gripping  any  cylindrical  ring  or  collar 
which  may  approximately  fit  its  periphery. 


*  Cut  taken  from  article  by  Oral  B.  French  in  "American  Machinist,"  vol.  27, 
page  353. 


244 


MACHINE-SHOP  TOOLS  AND  METHODS 


In  some  cases,  instead  of  being  screwed  on  the  spindle,  the  small 
chuck  is  made  to  fit  an  arbor  which  is  held  by  friction  in  the  spindle- 
socket.  Such  chucks,  because  of  the  limited  friction  of  the  socket,  can- 
be  used  on  small  work  only. 

Wood  Chucks. — Once  when  a  certain  instructor  was  talking  to  his 
class  about  chucks  a  farmer  student  had  the  hardihood  to  propose  the 
wood  chuck  as  a  subject  for  discussion.  This  led  the  instructor  to  expa- 
tiate on  the  advantages  of  the  wood  chuck  as  a  mechanical  device,  and 
to  show  how  a  simple  block  of  wood  could  be  bolted  to  the  face-plate,  and 
bored  or  turned  to  receive  a  frail  piece  of  work  which  might  be  sprung 
out  of  shape  if  held  in  the  common  chuck.  The  work  should  be  driven 
on  or  in  the  chuck  with  a  wooden  mallet  or  with  a  block  of  wood  and 
hammer. 

In  gripping  light  frail  pieces  in  the  ordinary  chuck  it  is  generally 
necessary  to  slacken  the  jaws  after  the  roughing  cuts  have  been  taken 
in  order  to  allow  the  work  to  assume  its  natural  shape  before  the  final 
cuts  are  made.  After  loosening  the  screws  they  should  be  tightened 
again  just  enough  to  take  up  the  lost  motion.  Otherwise  the  work 
may  be  pulled  out  of  the  chuck  by  the  cut. 

Testing  the  Concentricity  of  Chuck  Work. — Rough  castings,  etc.,  may 
be  tested  by  chalk  held  in  the  fingers,  or  by  a  tool  in  the  tool-post.  The 


point  where  the  chalk  or  tool  touches  indicates  which  chuck  jaws  are  to 
be  moved.  Work  which  has  been  machined  can  be  more  accurately 
adjusted  in  connection  with  an  indicator.  Fig.  355  shows  a  gear  held  hi 


METHODS  OF  DRIVING  WORK  IN  THE  LATHE  245 

a  chuck  and  being  tested  with  a  Bath  indicator.  This  instrument  is 
so  constructed  that  a  movement  of  .001"  on  the  testing  finger  is 
multiplied  to  show  either  1/i2  or  I/Q"  movement  of  the  dial  finger. 

Other  chucks  and  chucking  methods  are  discussed  elsewhere  in  this 
work. 


CHAPTER  XVI 
LATHE-ARBORS,  OR  MANDRELS,  AND  ARBOR-PRESSES 

Definition  and  Classification  of  Arbors. — An  arbor,  or  mandrel,  is  a 
bar  of  metal  designed  to  drive  work  in  the  lathe  by  friction  of  the  work 


FIG.  356. 


on  the  arbor.     Arbors  may  be  classified  as  follows:    First,  plain  arbor 
(Fig.  356);  second,  the  self-tightening  arbor  (Fig.  357);  third,  expansion- 


/Tighteriing.Ro'ller 


FIG.  357. 


arbors  (Figs.  358  and  359);   fourth,  arbor  for  tapering  work  (Fig.  360); 
fifth,  nut-arbors  (Figs.  361,  362,  and  363). 

The  Plain  Arbor  is  a  bar  of  steel  or  iron  turned  slightly  tapering  with 
a  flat  place  at  each  end.     Arbors  are  usually  driven  in  the  lathe  by  a 


•  FIG.  358. 

lathe-dog,  and  the  flat  place  on  each  end  is  the  bearing  for  the  set-screw 
of  the  lathe-dog.     They  are  made  tapering  to  compensate  for  slight 

246 


LATHE-ARBORS,   OR  MANDRELS,  AND  ARBOR-PRESSES        247 

variation  of  sizes  of  holes  in  the  work.  The  amount  of  taper  is  generally 
about  .01"  per  foot.  The  host"  plain  arbors  are  made  of  tool  steel, 
hardened  and  ground.  & 

In  hardening  the  arbor  it  is  somewhat  distorted,  and  to  compensate 
for  this  it  must  be  turned  about  .02"  larger  than  the  finished  size. 
The  remainder  of  the  material  is  ground  off  in  the  universal  grinder, 
and  being  tapering,  the  middle  of  the  arbor  is  the  nominal  size.  Before 
grinding  the  arbor  the  centers  should  be  carefully  lapped. 

The1  Self-tightening  Arbor  is  made  in  two  parts,  the  main  part  being 
similar  to  the  plain  arbor,  with  the  exception  that  it  is  parallel  in  diameter 
and  has  a  groove  cut  in  one  side.  Inserted  in  this  groove  is  a  small 


MffifififffiiiH 


FIG.  359. 

roller,  marked  T  in  the  figure.  The  groove  is  so  shaped,  and  the  roller 
is  of  such  a  diameter,  that  should  the  work  start  to  turn  on  the  arbor, 
the  roller  would  be  forced  into  the  space  between  the  work  and  the 
arbor,  thus  forming  a  kind  of  wedge  to  tighten  the  work  on  the  arbor. 
This  arbor  is  open  to  the  objection  that  the  means  for  tightening  the 
work  tends  to  make  the  work  eccentric.  The  amount  of  eccentricity, 
however,  will,  if  the  work  fit  the  arbor  fairly  snug,  be  so  small  as  to  be 
of  little  importance,  except  in  high-grade  work.  If  the  self-tightening 
arbor  be  used  in  turning  a  gear  or  other  detail  which  is  to  be  held  on 
its  shaft  by  set-screw  or  key,  the  line  of  contact  of  the  tightening  roller 
in  the  bore  of  the  detail  should  be  marked  and  the  set-screw  or  key  should 
be  located  on  this  line.  The  work  will  thus,  when  placed  upon  its  shaft, 
run  more  nearly  true  than  if  turned  on  the  plain  arbor.  This  suggests 


248 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  most  accurate  way  of  turning  a  detail  held  by  key  or  set-screw, 
viz.,  turning  it  on  its  own  shaft  with  the  set-screw  or  key  tightened. 

The  Expansion -arbor,  illustrated  in  Fig.  358,  is  made  in  two  parts, 
A  and  B.  Part  A  is  like  the  plain  arbor,  except  that  the  taper  is  very 
much  greater.  The  part  B  has  a  taper  corresponding  to  the  taper  of  A} 
and  has  three  longitudinal  slots,  two  of  which  are  cut  nearly  through, 
and  the  third  cut  entirely  through,  the  bushing  B.  To  use  this  arbor, 
part  A  is  driven  out  of  B  and  B  placed  in  the  work.  A  is  then  driven 
into  B,  causing  B  to  expand  and  grip  the  work.  B  is  always  made  par- 
allel on  the  outside. 

In  Fig.  359  is  shown  an  expansion-arbor  which  has  recently  been 
placed  upon  the  market.  The  outer  part  of  this  arbor  is  a  spiral  spring 
and  this  spring  is  bored  tapering  to  fit  the  inner  part,  which  is  similar 
to  that  of  the  preceding  paragraph.  The  outer  part  or  bushing  is  made 
of  spring  steel  and  the  inner  part  or  plug  of  tool  steel,  both  being  hardened 
and  ground. 

The  Arbor  for  Tapering  Work,  shown  in  Fig.  360,  is  made  in  three 
parts.  The  main  part  of  the  arbor  A  is  cone  shaped  at  one  end,  and 


Work 


.Cone' 


FIG.  360. 


I-IG.  3ol. 


the  other  end  carries  a  freely  fitting  cone  which  may  be  adjusted  toward 
the  first  cone  by  means  of  the  thread  and  nut.  The  work  to  be  turned 
is  placed  upon  the  arbor  with  the  large  end  of  the  hole  toward  the  fixed 
cone;  the  movable  cone  is  then  forced  into  the  small  end  of  the  hole, 
thus  gripping  the  work  concentric  with  the  axis  of  the  arbor.  In  using 
such  an  arbor  as  this  on  frail  work  care  should  be  taken  to  avoid  strain- 
ing the  work  by  forcing  the  movable  cone  too  tightly  into  the  hole. 
Work  having  a  taper  of  say  3/4"  per  foot,  or  less,  may  be  driven  by  a  single 
tapering  arbor  made  of  one  piece,  without  nut  and  movable  cone.  The 
arbor  shown  in  Fig.  360  could  be  used  for  work  with  a  parallel  hole, 
but  it  is  not  well  adapted  to  such  work. 

Nut-arbors. — Fig.  361  illustrates  the  simplest  form  of  nut-arbor.     It  is 
essentially  a  plain  arbor  with  thread  cut  on  one  end.     The  nut  to  be 


LATHE-ARBORS,  OR  MANDRELS,   AND  ARBOR-PRESSES        249 

faced  is  screwed  on  the  threaded  end  of  the  arbor,  the  whole  placed 
between  the  lathe-centers  and  one  end  of  the  nut  faced  off  with  a  common 
side-tool.  The  arbor  is  then  take,n  out  of  the  lathe,  the  nut  reversed, 
and  the  other  side  faced."  This  form  of  arbor  answers  fairly  well  when 
the  nut  fits  the  arbor  tightly,  but  when  it  fits  freely,  as  it  often  does, 
the  base  of  the  nut,  which  in  the  rough  is  not  at  right  angles  with  its 
axis,  will  be  forced  to  coincide  with  the  shoulder  on  the  arbor  and  thus 
the  nut -will  be  forced  "out  of  true."  This  form  of  arbor,  while  cheap 
in  construction,  is  unsatisfactory  in  operation. 

A  better  form  is  shown  in  Fig.  362.  This  arbor  carries  a  loosely 
fitting  washer  one  end  of  which  is  flat  and  the  other  end  concave.  The 
concave  end  fits  a  correspondingly  convex  shoulder  on  the  arbor.  When 


Lathe  Spindle 


asher 


FIG.  362. 


Washer 
FIG.  363. 


the  nut  is  screwed  against  this  washer,  the  washer  revolves  around  the 
curved  shoulder  of  the  arbor,  and  thus  accommodates  any  irregularity 
that  there  may  be  in  the  base  of  the  nut.  The  axis  of  the  threaded  hole 
is  by  this  means  allowed  to  conform  to  the  axis  of  the  arbor.  This 
is  necessary  for  correct  results. 

There  is  one  difficulty  common  to  both  Figs.  361  and  362,  viz.,  the 
arbor  must  be  taken  from  the  lathe  in  order  to  reverse  the  nut.  This 
difficulty  is  obviated  in  Fig.  363,  which  shows  an  arbor  so  designed 
that  it  may  be  screwed  on  the  lathe-spindle.  In  this  case  it  is  only  neces- 
sary to  stop  the  lathe  and  unscrew  the  nut  and  reverse  it  without  taking 
the  arbor  from  the  lathe.  This  form  of  arbor  has  the  additional  advan- 
tage that  it  does  not  require  any  lathe-dog  to  drive  it. 


FIG.  364. 

Some  mechanics  make  nut-arbors  with  slots  cut  in  the  threaded  end, 
as  shown  in  Fig.  364.     In  using  this  arbor  the  tail  spindle  of  the  lathe 


250 


MACHINE-SHOP  TOOLS  AND  METHODS 


is  screwed  up  somewhat  tighter  than  usual,  thus  expanding  the  arbor 
and  tightly  gripping  the  nut.  The  nut  should  not  be  screwed  against 
the  shoulder  until  it  has  been  gripped  by  the  expanding  arbor,  and 
then  it  should  barely  touch  the  shoulder.  This  arbor  could  be  made 
without  the  shoulder. 

Arbors  in  Large  Work. — It  is  found  that  on  very  large  work  (say  24" 
and  larger)  with  a  comparatively  small  hole,  the  friction  between  the 
work  and  the  arbor  (not  nut  arbor)  is  insufficient  to  drive  ,the  work 
If  such  work  admits  of  being  clamped  directly  to  the  face-plate  of  the 
lathe,  the  arbor  may  be  dispensed  with  and  the  work  driven  by  means 
of  bolts  securing  the  work  to  the  face-plate.  In  the  case  of  a  pulley,  as 
illustrated  in  Fig.  365,  the  arbor  may  be  used  to  support  the  pulley 


FIG.  365. 

and  the  pulley  may  be  driven  by  means  of  two  studs  secured  to  the 
face-plate  and  engaging  with  the  arms  of  the  pulley.  Should  the 
pulley  fit  near  the  middle  of  the  arbor  rather  than  on  the  end,  we  could 
use  two  latne-dogs  to  drive  it.  One  of  these  lathe-dogs  would  be  driven 
by  the  face-plate  of  the  lathe  or  a  stud  projecting  from  the  latter; 
the  tail  of  the  second  dog  would  engage  with  one  of  the  arms  of  the 
pulley.  This  method  is  not  quite  so  satisfactory  as  the  first  described. 

Methods  of  Forcing  Arbors  into  the  Work. — The  simplest  method 
of  forcing  an  arbor  into  the  work  is  by  means  of  a  block  of  hardwood 
and  a  hammer.  A  better  method  is  to  dispense  with  the  block  of  wood 
and  use  one  of  the  forms  of  soft  hammers  previously  described.  A 
still  better  method  is  to  use  some  form  of  arbor-press.  Two  different 
designs  of  these  machines  are  shown  below. 

In  using  a  common  hammer  to  force  the  arbor  into  the  work  we  should 
never  strike  the  arbor  directly  with  the  hammer.  Striking  the  arbor  with  a 


LATHE- ARBORS,  OR  MANDRELS,  AND  ARBOR-PRESSES        251 

common  steel  hammer  injures  the  center  in  the  arbor  and  thus  causes 
the  arbor  to  revolve  eccentrically."  For  this  reason  greater  care  is  taken 
in  making  the  centers  in  lathe  arbors  than  in  ordinary  work.  In  making 
the  lathe-arbor  it  is  first  centered  in  the  usual  manner,  and  then  the 


FIG.  366. 


countersink  of  the  center  is  beveled  on  its  outer  edge  with  a  counter- 
sinking drill  of  greater  angle.  This  leaves  the  vital  part  of  the  center 
slightly  below  the  end  of  the  arbor,  and  thus  it  is  protected  to  some 
extent  from  the  abuse  of  careless  workmen. 


252 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  3f>7. 


LATHE-ARBORS,  OR  MANDRELS,  AND  ARBOR-PRESSES        253 

The  diameter  of  the  countersink  in  a  lathe-arbor  should  be  about 
twenty-five  per  cent  larger  than  given  for  ordinary  work  in  the  chapter 
on  Lathe-centers,  etc.  As  stated,,  the  centers  should  be  lapped.  The 
instructions  given  in  Chapter  X  for  lapping  reamer- centers  apply  equally 
well  to  arbor-centers. 

Special  Arbors  for  Large  Work. — The  arbors  previously  described 
are  used  for  work  of  ordinary  size,  but  when  it  is  necessary  to  use  an 
arbor  for  extra-large  work  we  have  to  make  a  special  arbor.  This  may 
be  done  by  shrinking  on,  or  otherwise  securing  cast-iron  rings  or  collars 
to  a  small  shaft.  The  shaft  may  be  of  any  convenient  size  to  give 
sufficient  rigidity,  the  extra  diameter  being  provided  for  by  the  cast- 
iron  collars. 

When  a  great  many  pieces  are  to  be  machined,  it  may  be  desirable 
to  make  the  arbor  of  cast  iron,  with  the  enlarged  part  cast  on  rather 
than  shrunk  on.  When  thus  "constructed  it  is  well  to  have  steel  plugs 
inserted  in  the  ends  of  the  arbor  to  receive  the  work  centers.  On  ac- 
count of  the  great  weight  and  friction,  oil-holes  should  be  drilled  from 
the  outer  diameter  of  the  shaft  through  shaft  and  plug.  This  arrange- 
ment will  facilitate  oiling  the  centers. 

Arbor-presses.  —  In  Fig.  366  is  shown  an  arbor-press  designed  to 
be  operated  by  hand.  In  using  this  machine  the  work  is  placed  on 
the  plate  P,  and  the  arbor  is  forced  into  the  work  by  the  ram  R  which 
is  operated  by  the  lever  L.  The  connection  between  the  lever  and  the 
ram  is  made  by  means  of  a  train  of  spur-gears,  the  last  of  which  en- 
gages the  rack  teeth  on  the  ram.  The  lever  has  a  ratchet  connection 
with  its  shaft,  which  with  the  hand-wheel  H  admits  of  quick  return 
of  the  ram.  Both  ram  and  lever  are  counterweighted.  These  ma- 
chines are  made  in  smaller  sizes  also,  some  of  which  are  designed  to  be 
secured  to  the  bed  of  the  lathe. 

The  arbor-press  illustrated  in  Fig.  367  was  designed  in  connection 
with  a  class  in  machine  design  at  the  Michigan  Agricultural  College. 
The  operation  of  the  machine  by  means  of  the  hand-wheel  H,  worm- 
wheel  W,  and  rack  and  pinion  will  be  understood  from  the  cut. 


CHAPTER  XVII 
SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 

Character  of  the  First  Two  Examples. — This  chapter  contains  de- 
tailed instructions  for  a  few  examples  in  lathe  work,  the  exercises  chosen 
being  such  as  involve  principles  admitting  of  general  application.  The 
first  two  examples  are  a  plain  cylinder  or  shaft,  and  a  collar,  both  of 
which  are  to  be  finished  all  over  and  polished.  The  collar  is  to  be 
finished  to  dimensions  in  connection  with  standard  gages;  but,  suppos- 
ing the  work  to  form  the  basis  for  actual  exercises  in  a  college  shop,  it 
might  be  well  to  use  common  calipers  in  fitting  the  shaft  to  the  collar. 
The  exercises  would  then  give  practice  in  both  methods  of  accurate 
measurement.  The  shaft  is  supposed  to  be  machine  steel,  and  it  is  to 
be  finished  to  !1/2//  diameter  by  6"  long.  The  collar  is  cast  iron,  the  fin- 
ished dimensions  being  3"  diameter  by  I3//'  long,  and  it  is  to  be  a  tight 
fit  on  the  shaft.  Both  details  have  the  usual  stock  allowances  for 
finish. 

Machining  the  Collar. — (1)  Grip  the  collar  in  the  independent  chuck 
so  that  its  outer  face  shall  project  beyond  the  chuck  jaws  as  in  Fig.  368. 
This  gives  clearance  for  the  facing-tools.  The  boring-tools  must  clear 
the  spindle  and  chuck-plate  on  the  rear  end  of  the  collar. 

(2)  Rough-face  the  collar  with  a  roughing-tool,  as   shown  at  J  in 
same  figure,  or  with  the  diamond-point  tool  D  in  Fig.  369.     Slightly 
chamfer  the  corner  at  C,  to  protect  the  finishing-tool  from  the  foundry 
scale. 

(3)  Bore  the  collar  with  a  boring-tool  as  shown,  to  within  about  .008" 
of  final  diameter.     Do  not  waste  time  by  boring  to  any  exact  dimen- 
sion, as  the  reamer  is  designed  for  this  purpose.     Some  use  two  sizes 
of  reamers,  to  avoid  boring  even  to  the  approximate  dimensions  indi- 
cated. 

(4)  Ream  to  size  with  a  fluted  or  rose  reamer,  using  no  lubricant. 

(5)  Test  with  plug-gage  or  caliper-gage.     If  the  gage   cannot  be 
pushed  through  with  the  forefinger,  run  the  lathe  at  a  high  speed  and 
smooth  the  bore  with  emery-paper  wrapped  around  a  stick,  as  shown 

254 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


255 


in  Fig.  369,  or  held  in  the  fingers.  In  using  the  emery-paper  it  will 
require  care  to  avoid  enlarging  the  hole  at  each  end.  If  the  hole  is 
found  to  be  smaller  at  the  back  end  apply  the  emery  most  at  that  end. 
If  the  gage  will  not  passr  through  the  bore  after  a  few  minutes'  applica- 
tion of  the  emery-cloth,  the  reamer  should  be  enlarged.  Or,  if  available, 
an  expanding  reamer  would  be  advantageous  for  use  in  following  the 
previous  reamer  when  the  latter  is  worn  below  size. 

If  no  reamers  are  to  be  used,  regrind  and  oil-stone  the  boring- tool 
and  finish  to  final  size,  taking  care  to  feed  the  carriage  back  and  forth 


FIG.  368. 


FIG.  369. 


FIG.  370. 


to  compensate  for  the  spring  of  the  tool;  or,  finish  with  a  second  boring- 
tool  kept  for  finishing  cuts,  which  tool  may  have  a  somewhat  broader 
cutting-edge.  Test  with  gage  as  before. 

(6)  Finish  the  outer  face  of  the  collar  with  a  bent  side-tool  as  at  C, 
Fig.  370,  or  with  a  diamond-point  as  at  D,  or  with  a  diamond-point 
tool  as  at  M.  The  advancing  corner  of  the  tool  should  be  slightly  rounded 
with  the  oil-stone.  By  giving  either  of  these  tools  small  contact  with 
the  work,  and  running  the  lathe  from  50  to  100  per  cent  faster  than 
for  the  roughing  cuts,  a  surface  may  be  made  which  will  require  only 
the  final  polishing  with  emery-cloth.  But  some  workmen  never  learn 
how  to  grind  and  oil-stone,  and  set  the  tool  so  as  to  get  this  nice  scrap- 
ing effect  without  chattering.*  These  men  prefer  to  run  the  lathe  but 

*  The  chattering  may  sometimes  be  overcome  by  careful  adjustment  (a)  of 
the  spindle  end-thrust,  (6)  of  the  spindle  bearings,  (c)  of  the  cross  slide-gibs,  (d)  of 


256 


MACHINE-SHOP  TOOLS  AND  METHODS 


little  faster  for  the  finishing  cut  than  for  roughing  cuts,  and  to  use  a 
file  or  scraper  for  smoothing.  To  get  the  best  results  in  finishing  cuts, 
corner  E,  Fig.  370,  should  clear  about  .001"  while  the  point  of  the  tool  is 
cutting. 

(7)  Having  smoothed  the  face  of  the  collar,  it  may  next  be  polished 
with  oil  and,  say,  Nos.  l/2  and  00  emery-cloth,  the  00  being  used  last. 
Run  at  highest  speed  and,  with  emery-cloth  wrapped  around  a  flat 
stick  or  around  a  file,  move  it  slowly  back   and  forth  over  the  face 
of  the  work;    or,  hold  the  cloth  between   the  end  of  stick  and  work, 
the  stick  being  fulcrumed  over  a  tool  in  tool-post. 

Some  would  prefer  to  do  this  polishing  after  all  the  turning  is  com- 
pleted, which  is  all  right  if  the  face  of  the  collar  overhangs  the  end  of 
the  arbor  or  a  shoulder  on  same.  Otherwise  it  is  difficult  to  polish  the 
whole  face  equally  without  wearing  the  arbor  with  emery. 

(8)  Place  the  collar  on  an  expansion  arbor  *  so  that  its  rough  end 
shall  overhang  the  right  end  of  the  arbor  bushing  about  l/4".     Rough- 
turn  the  periphery,  using  a  right-hand  diamond-point  tool,  as  at  A  in  Fig. 
371,  or  a  roughing-tool,  and  leaving  about  .01"  for  the  finishing  cut. 


FIG.  371, 


FIG.  372. 


FIG.  373. 


(9)  Rough-face  the  right  end  of  the  collar  with  same  tools  used  in 
operation  No.  2,  leaving  not  more  than  .01"  for  the  finishing  or  smooth- 
ing cut. 

the  carriage-gibs.  In  other  cases  the  tool  contact  must  be  reduced  or  its  clear- 
ance and  rake  lessened.  Merely  changing  the  direction  of  the  feed  may  some- 
times stop  the  chattering.  When  turning  work  on  centers,  a  bit  of  leather  or  waste 
between  the  tail  of  the  dog  and  the  driver  may  cause  the  trouble  to  cease.  The 
causes  of  chattering  are  referred  to  in  other  connections  in  this  work. 

*  If  the  solid  or  plain  arbor  be  used  the  work  will  generally  fit  near  the  mid- 
dle, necessitating  special  care  to  avoid  injuring  the  arbor  with  the  tools  and  emery, 
and  leaving  the  edge  of  the  bore  in  such  shape  as  to  require  the  use  of  file  and 
emery-paper  by  hand  after  removing  the  collar.  The  plain  arbor  is,  nevertheless, 
often  used  for  such  work. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK  257 

(10)  Smooth-face  this  end  according  to  instructions  for  operation 
No.  6,  except  that  a  straight  t  side- tool  may  be  used  if   preferred.     If 
the  end  is  to  be  filed  or  scraped,  ajlow  as  f°r  nmiS>  e^c.,  in  next  numbered 
paragraph;   but  if  emery-cloth  only  is  to  be  used,  an  allowance  of  not 
more  than  .001"  should  be  made. 

(11)  Smooth-turn  the  periphery  with  a  square-nose  tool,  or  with 
a  left  diamond-point  tool  set  as  at  0  in  Fig.  371,  and  having  its  point 
slightly  rounded.     The  part  0  of  this  tool  should  just  clear  the  work 
\\hile  the  tool  is  fed  in  the  direction  of  the  arrow.     The  periphery  of 
the  collar  is  very  likely  to  need  filing,  and  for  the  file  and  emery-cloth 
an  allowance  of  from  .001"  to  .005"  should  be  left  after  the  finishing 
cut.*     The  beginner  is  here  cautioned  against  leaving  too  much  work 
for  the  file,  as  filing  tends  to  destroy  the  truth  of  cylindrical  surfaces. 

(12)  File  periphery,  and  face  also  if  necessary,  leaving  about  .0005" 
for  polishing.     Polish  periphery  and  right  end  according  to  previous 
instructions,  testing  diameter  and  length  by  standard  gages.     Work  of 
this  character  is  not  to  have  round  corners  unless  so  shown  on  drawing 
or  specified,  but  it  is  a  sign  of  poor  workmanship  when  the  corners  are 
left  so  sharp  as  to  cut  the  hand.     Dull  the  corners  with  emery-cloth 
and  remove  the  collar  from  the  arbor. 

Machining  the  Shaft.  -  -  (1)  Saw  from  a  !9/ie"  or  !5/8"  bar  of 
machine  steel,  a  piece  §l/\s"  to  6l/s"  long,  and  center  according  to 
instructions  in  Chapter  XIV. 

(2)  The  next  operation  is  to  face  the  ends.  If  there  is  as  much 
as  Vie"  to  cut  off,  face  off  all  but  about  .01"  with  the  roughing-tool, 
which  will  leave  the  end  as  shown  in  Fig.  372.  Cut  off  the  projection  P 
with  a  side-tool,  moving  the  latter  parallel  with  the  axis  of  the  shaft 
and  at  the  same  time  feeding  in.  Next  run  the  lathe  faster  and  take 
one  or  two  light  smoothing  cuts.  For  this  purpose,  as  well  as  for  cut- 
ting away  the  projection  left  by  the  roughing-tool,  the  side-tool  should 
have  its  point  about  45°  angle,  as  in  Fig.  373,  and  it  should  be  set 
so  as  to  touch  at  A  and  barely  clear  at  B.  In  this  work  the  tool  should 
be  fed  at  right  angles  to  the  shaft-axis.  Next,  change  the  lathe-dog 
and  finish  the  other  end  in  the  same  manner.  Measurement  with  the 
steel  rule  is  in  most  cases  sufficiently  accurate  for  shaft  lengths. 


*  Most  mechanics  make  these  small  allowances  by  merely  setting  the  calipers 
"a  trifle"  larger;  but  the  tendency  is  toward  more  systematic  methods.  Microm- 
eter or  Vernier  calipers  may  be  used,  either  for  direct  measurement  or  for  setting 
the  common  calipers.  In  some  such  cases  limit-gages  would  be  advantageous. 


258  MACHINE-SHOP  TOOLS  AND  METHODS 

If  after  facing  the  ends  it  is  found  that  the  depth  of  the  center  has 
been  too  much  reduced,  drill  and  ream  it  again. 

(3)  As  a  general  rule  a  shaft  or  other  detail  which  is  to  be  machined 
should  be  roughed  out  all  over  to  approximately  the  final  dimensions 
before  any  part  (ends  excepted)  is  finished.     In  the  case  of  a  shaft  this 
gives  both  centers  time  to  wear  to  a  bearing,  and  they  are  not  likely  to 
change  afterward;  but  if  the  shaft  be  finished  half-way  and  then  reversed 
eccentricity  will  probably  result.    Another  reason  for  roughing  out  the 
work  is  that  there  are  initial  stresses  in  the  outer  fibers  of  the  metal. 
When  these  stresses  are  removed  by  cutting  away  the  metal  the  detail 
usually  changes  its  shape.     In  heavy  stocky  details  the  change  is  some- 
times inappreciable,  and  is  therefore  often  neglected;    but  in  pieces  of 
which  the  diameter  or  thickness  is  small  as  compared  with  the  length, 
changes  are  expected. 

With  the  above  in  view  turn  the  shaft  about  half  its  length  to  within 
.02"  to  .03"  of  final  diameter,  using  the  same  tools  as  used  for  the 
roughing  cut  on  the  collar.  Change  the  lathe-dog  and  turn  the  opposite 
end  in  a  similar  manner. 

(4)  The  finishing  cuts  may  now  be  taken.     With  the  point  of  the 
diamond-point  tool  slightly  rounded  and  the  tool  set  as  at  0  in  Fig.  371, 
turn  the  shaft  to  within  .01"  of  final  size.     With  another  tool  of  same 
shape  reserved  for  finishing  cuts  on  steel,  or  with  the  same  tool  nicely 
oil-stoned,  take  the  final  cut,  leaving  about  .0015"  for  file  and  emery- 
cloth.     Reverse  and  finish  opposite  end.     The  last  cuts  should  be  taken 
with  finer  feed  *  and  higher  speed  than  the  preceding  cuts. 

Common  calipers  are  to  be  used  according  to  instructions  in  Chapter  I 
for  fitting  the  shaft.  Most  workmen  would  fit  one  end  for  a  short  distance 
and  use  this  as  a  guide  for  filing  and  polishing  the  remainder  of  the  shaft. 

(5)  File  and  polish  the  whole  length  of  the  shaft,  using  the  arbor-press 
or  a  soft  hammer  in  testing  its  fit  in  the  collar.      The  shaft  must  not  be 
forced  in  too  tightly,  and  it  should  be  oiled  to  prevent  "  seizing. " 

Examples  of  Taper-turning,  etc.— The  uses  of  the  ordinary  facing-, 
turning-,  and  boring-tools  which  have  been  considered  somewhat  in  detail 
in  connection  with  the  two  examples  of  work  just  given,  will  be  referred 

*  For  instruction  on  cutting  speeds  and  rates  of  feeding  the  reader  is  referred 
to  Chapter  XI.  As  to  the  number  of  cuts  required,  it  is  difficult  to  give  a  rule. 
With  the  ordinary  stock  allowance,  one  or  two  roughing  cuts  will  generally  be  suffi- 
cient in  boring  a  cored  hole.  It  may  require  as  many  or  more  finishing  cuts.  With 
same  stock  allowance,  the  workman  should  aim  to  make  one  roughing  and  one  or 
two  finishing  cuts  answer  for  peripheral  turning  and  for  facing. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


259 


to  more  briefly  in  the  remainder  of  this  chapter.    The  next  example  is 
the  bevel-gear  blank  shown  in  fig.  374,  and  the  operations  are  as  follows: 

(1)  Measure  blank  to  ascertain  if  there  is  sufficient  stock  and  how 
it  is  distributed.     Chuck  as  shown 

in  Fig.  375  and  finish*  at  F. 

(2)  Work  in  which  a  small  hole 
is  wanted  is  often   left  solid  by 
the  moulder.     In  a  case  like  the 
one  in  hand  the  first  thing  toward 
making  the  hole  is  to  cut  a  center 
for  the  drill.     For  this  purpose  we 
do  not  use  a  center-punch,  but  a 
centering-tool  like  that  shown  in 
Fig.  376.    The  cutting-end  of  this 
tool  is  exactly  like    a  flat  drill, 
but  the  shank  is  that  of  a  com- 
mon lathe  tool,  and  it  is  held  in 
the  tool-post  in  the  same  manner. 
This  tool  is  adjusted  in  the  tool- 
post    as   nearly  in  line  with   the 
center  as  may  be  done  by  the  eye, 

and  then  moved  against  the  revolving  work  by  the  hand-feed  handle  of 
the  lathe-carriage.  If  it  makes  a  circle  larger  in  diameter  than  its  ex- 
treme point,  it  must  be  readjusted  to  strike  the  center  of  this  circle, 
and  then  pressed  against  the  work  until  it  cuts  a  conical  hole  the  largest 
diameter  of  which  may  be  about  3/8"  to  5/s">  provided  the  required 
bore  is  larger,  as  it  is  in  this  gear.  If  the  tool  cuts  eccentrically,  the 
carriage  and  cross-slide  gibs  should  be  looked  after  and  tightened  if 
loose,  and  the  tool  should  be  fed  outward  so  as  to  cut  on  one  side  until 
the  eccentricity  is  corrected. 

(3)  The  hole  should  next  be  drilled.  A  twist-drill  l/1Q"  to  l/8" 
smaller  than  the  final  bore,  and  held  in  the  holder  shown  in  Fig.  188, 
or  in  the  tail-spindle  socket,  or  in  a  holder  made  to  clamp  on  the  end 
of  the  tail-spindle,  may  be  used.  Only  small  drills  should  be  held  in  the 
tail-spindle  socket,  as  .the  slipping  of  the  larger  drills  would  injure  the 
socket  and  disturb  the  fit  of  the  lathe-center.  When  the  common 
holder  is  used,  it  requires  care  to  keep  the  drill  from  drawing  in  and 


FIG.  374. 


*  The  word  finish,  used  in  a  general  sense,  includes    both   rough  and  smooth 
cuts. 


260 


MACHINE-SHOP  TOOLS  AND   METHODS 


leaving  the  tail-center,  especially  when  the  point  of  the  drill  is  emerging 
through  the  bottom  of  the  hole.  For  safeguards  against  this  trouble 
see  Chapter  IX. 

(4)  Enlarge  the  hole  with  boring-tool  to  within  a  few  thousandths 
of  an  inch  of  the  final  diameter  and  then  finish  with  a  fluted  or  rose 


<— F 


c 


FIG.  376. 


reamer;  or,  bore  somewhat  smaller  and  use  a  rose  reamer,  followed 
by  a  fluted  reamer.  Test,  and  if  too  small  follow  instructions  given 
for  a  similar  case  near  the  beginning  of  this  chapter. 

(5)  Place  on  arbor  and  turn  largest  diameter  to  size.     This  will 
leave  a  cylindrical  surface  upon  which  to  mark  a  line  for  the  edge  E* 
Establish  this  line  with  respect  to  the  face  F.    The  exact  position  of  this 
face  is  generally  not  very  important. 

(6)  Turn  face  /  to  the  required  angle,  starting  at  the  above  edge  line 
and  using  the  compound  rest  R  1,  a  cut  of  which  is  shown  in  Fig.  232. 
Use  a  gage  if  the  lathe  has  no  compound  rest.     In  using  the  compound 
rest,  the  workman  is  apt  to  make  a  mistake  if  the  angle  on  the  drawing 
is  not  given  the  same  way  that  the  compound  rest  is  graduated.     Thus 
the  compound  rest  is  at  zero  when  set  to  cut  parallel  with  the  cross- 
feed.     The  angles  on  beveled  work  should  be  given  from  the  same 
starting-point,  but  if  given  from  the  axis,  as  in  Fig.  374,  the  compound 


*  The  position  of  this  edge  should  be  given  on  the  drawing.     See  article  by 
the  author  in  "American  Machinist,"  vol.  27,  page  967. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


261 


rest  must  be  set  to  the  complement  of  the  angle  given.  The  complement 
of  the  angle  is  the  angle  itself  subtracted  from  90°.  If,  for  instance, 
the  angle  with  axis  be  47°,  as  i^  is  in  this  case,  the  rest  should  be  set 
to  90° -47°  =  43°. 

(7)  Turn  surface  G,  starting  from  the  edge  line,  and  then  turn  D  to 
give  face  H  the  proper  length. 

(8)  Finish  hub  end  and  back  face,  and  then  finish  hub  diameter. 
The  horizontal  distance  between  end  of  hub  and  edge  line  E  must  usually 
be  quite  accurate. 

If  required  to  turn  the  bevel-gear  in  a  lathe  having  plain  rest  only, 
a  gage  could  be  used  as  shown  in  Fig.  377 ;  and  after  rough-turning  the 


CUTTING  BEVZL  BY 
STEPS 


GAGE 


SET  BY  GAGE' 


FIG.  377. 


FIG.  378. 


face,  it  could  be  finished  with  a  side-tool,  or  in  steps  with  square- 
nose  tool  as  in  Fig.  378.  Either  of  these  tools  could  be  set  by  the  gage. 
In  using  the  square-nose  tool  the  width  of  each  step  should  be  about 
three  fourths  the  width  of  the  tool-edge.  In  this  way  the  depth  of  each 
step  will  be  indicated  by  the  preceding  cut.  The  steps  should  be  started 
at  the  large  diameter.  The  face  may  be  smoothed  with  a  file. 

The  lathe-center,  which  is  60°  included  angle,  is  often  turned  by  the 
above  method.  When  turning  the  center  by  compound-rest  method, 
the  rest  should  be  turned  to  the  left  60°.  Thus  the  angle  with  axis  is 
half  of  60°  =  30°  and  90° -30° -60°. 

Turning  and  Knurling  a  Center-punch. — To  make  a  center-punch 
like  Fig.  379  in  an  engine-lathe,  the  following  order  of  operations  may 
be  observed: 


262 


MACHINE-SHOP  TOOLS  AND  METHODS 


(1)  Saw  off  a  piece  of  5/g"  round  tool  steel  53/s"  long. 

(2)  Center,  face  ends  and  turn  body  to  9/i6"  diameter.     It  need 
not  be  particularly  smooth. 


FIG.  379. 


(3)  Fig.  380  shows  a  knurling-tool.     With  this  tool  in  tool-post  and 
pressed  tightly  against  stock,  both  knurls  being  in  contact  with  latter, 


FIG.  380 

feed  the  lathe-carriage  lengthwise  by  power.  Let  the  knurler  traverse 
the  work  as  many  times  as  may  be  necessary  to  make  it  appear  like 
Fig.  381.  The  knurled  surface  may  extend  about  3/8"  longer  than  the 
drawing,  the  extra  length  being  cut  away  in  succeeding  operations. 

(4)  Using  a  lathe  having  a  compound  rest,  chuck  stock,  allowing 
about  23/8"  to  project,  and  using  a  brass  sleeve  to  protect  knurling.    A 
draw-in  chuck  like  that  shown  in  Figs.  243  and  244  would  be  best  for 
this  work. 

(5)  With  side-tool  face  off  end  until  drilled  center  disappears. 

(6)  Turn  D,  adjusting  compound  rest  to  cut  angle  given  on  drawing. 

(7)  Readjust  rest  and  turn  point  E,  which  is  of  the  same  angle  as 
the  lathe-center  previously  referred  to. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


263 


(8)  Finish  with  file  and  polish  with  emery-cloth  and  oil. 

(9)  Mark  off  points  F  and  fr*  and  chuck,  allowing  end  H  to  project 
about  I3//'  and  using  brass  sleeye  as  before.     Face  off  end  to  mark  G. 


FIG.  381. 

(10)  With  compound  rest   properly  adjusted,  turn  H  to  angle  of 
drawing. 

(11)  Crown  the   end   approximately  with   roughing-tool,   finishing 
with  scraper  or  special  curved  tool.     File  and  polish  as  in  previous 
case. 

(12)  Temper  both  ends  about  the  same  as  for  cold-chisels. 


FIG.  382. 

Fig.  382  shows  a  knurling-tool  specially  adapted  to  frail  work.  This 
tool  was  illustrated  by  the  cut  here  used  in  "  American  Machinist," 
vol.  26,  page  1257. 

Turning  Tapers  by  Taper  Attachment  and  by  Tail-stock  Adjustment. 
—The  short,  abrupt  tapers,  to  which  the  compound-rest  method  is 
adapted,  are  generally  designated  in  degrees,  but  when  acute  angles 
are  referred  to  in  the  machine-shop,  they  are  ordinarily  designated 


264 


MACHINE-SHOP  TOOLS  AND  METHODS 


by  the  amount  of  taper  in  diameter  per  foot.  These  tapers  may  be 
made  either  by  setting  the  tail-stock  over  or  by  using  the  taper  attach- 
ment. The  latter  is  the  better  way,  but  many  lathes  lack  the  attach- 
ment. The  tail-stock  method  will  be  described  first.  Thus,  suppose 
we  require  a  piece  like  Fig.  383.  It  will  be  seen  that  the  taper  part 


t 

•  —  V 

"e* 

* 

1 

FIG.  383. 

has  a  taper  of  1"  per  foot.  This  would  seem  to  necessitate  setting 
the  tail-stock  over  just  a  half  inch.  This  is  a  close  approximation, 
but  on  account  of  the  peculiar  contact  between  the  work-centers  and 
the  lathe-centers,  and  because  the  distance  between  centers  is  changed 
slightly  when  the  tail-stock  is  set  over,  it  is  not  exact.  Assuming, 
however,  that  the  tail-stock  had  been  adjusted  correctly  for  the  above 
case,  still  it  would  not  be  right  for  a  shaft  2  feet  long  having  a  similar 
taper  end.  This  is  clearly  shown  in  the  diagram  of  Fig.  384,  which 


AXIAL  LINE  OF  CENTERS 


AXIAL  LINE,OF  WORK 
l__ 


12—-- 


--24 


•" *1 


FIG.  384 


represents  the  tail-stock  as  moved  back  to  take  in  a  shaft  2  feet  long. 
It  will  be  seen  that  it  has  left  the  axis  of  the  shaft  and  would  need  to 
be  set  over  to  the  dotted  position  of  the  center,  or  about  twice  as  far 
as  for  a  shaft  1  foot  long.  From  the  above  considerations  it  will  appear 
that  for  a  given  taper  per  foot  the  distance  that  the  tail-stock  must  be 
set  over  varies  with  the  length  of  the  shaft. 

The  Taper  Attachment  is  shown  bolted  to  the  rear  of  a  lathe-bed 
in  Fig.  236.  In  using  this  attachment  its  guide-bar  G  13  is  swiveled 
on  a  central  phi  an  amount  proportional  to  the  taper,  regardless  of  the 
length  of  the  shaft.  The  graduations  at  the  end  of  the  plate  upon 
which  the  guide  swivels  indicate  the  taper.  The  taper  attachment  is 
so  constructed  that  when  adjusted  to  any  required  taper  and  connected 
to  the  cross-slide  it  causes  the  latter  to  feed  in  or  out,  at  the  taper  to 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK  265 

which  the  attachment  is  set,  without  interfering  with  the  carriage-travel 
and  crosswise  adjustment  of  tool.  This  method  of  making  tapers  is 
simpler  than  the  tail-stock  method,  but  there  are  some  practical  diffi- 
culties in  its  operations,  due  to  necessary  freedom  of  movement  in  the 
machine-slides,  etc.  To  get  the  best  results  the  cut  should  be  started 
about  Y2"  beyond  the  end  of  the  work.  The  carriage  will  thus  travel 
a  short  distance  before  the  tool  begins  to  cut,  and  in  so  doing  the  lost 
motion  due  to  the  freedom  of  movement  above  mentioned  will  be  taken 
up.  If  we  neglect  this  precaution  the  tool  is  very  likely  to  cut  irregu- 
larly a  short  distance.  If  the  diameter  of  the  work  is  much  smaller 
than  the  lathe-center,  the  clearance  may  be  given  by  starting  the  feed 
with  the  tool  clearing  the  center  and  feeding  it  in  as  it  approaches  the 
work. 

Errors  in  Taper-attachment  Graduations. — In  this  connection  it 
may  be  proper  to  call  attention  to  an  error  in  the  graduation  of  taper 
attachments.  Topers  are  measured  at  right  angles  to  their  axes. 
The  graduations  of  the  taper  attachments,  however,  are  made  on  the 
arc  of  a  circle  concentric  with  the  pin  upon  which  the  guide  swivels. 
These  graduations  should  be  such  as  would  be  projected  from  equal 
divisions  of  a  line  drawn  tangent  to  the  graduated  arc  and  perpendicular 
to  the  axis  of  the  lathe.  This  would  make  the  subdivisions  on  the 
graduated  arc  farther  apart  for  the  greater  tapers  than  for  the  smaller 
tapers.  But  in  most  taper  attachments  the  graduated  arc  is  laid  out 
in  equal  divisions.  This  introduces  an  error  which  is  scarcely  notice- 
able in  small  tapers,  but  which  is  quite  appreciable  on  the  greatest 
tapers  for  which  these  attachments  are  designed.  However,  it  is  usu- 
ally more  important  to  have  the  inner  part  of  the  work  fit  the  outer 
part  than  to  have  the  exact  taper  per  foot. 

For  a  more  comprehensive  treatment  of  taper-attachment  gradua- 
tions the  reader  is  referred  to  "  Machinery,"  page  238,  January,  1904. 

Taper  attachments  are  usually  designed  to  turn  tapers  not  greater 
than  4"  per  foot.  The  maximum  length  of  the  taper  is  about  24"  to 
one  adjustment  of  the  attachment. 

Fitting  a  Taper-shaft  to  a  Collar. — Before  giving  instructions  for  this 
work  the  attention  of  the  student  should  be  called  to  some  further  pre- 
cautions necessary  in  taper-turning.  In  any  work  turned  on  the  lathe- 
centers,  the  work-centers  are  more  likely  to  wear  concentrically  if  the 
ends  are  faced  square  with  the  axis.  On  account  of  the  abnormal  con- 
tact of  the  centers  this  is  of  special  importance  in  turning  taper  work 
with  the  tail-stock  set  over.  When  making  tapers  with  the  taper  attach- 


266  MACHINE-SHOP  TOOLS  AND  METHODS 

ment  the  tail-stock  is  kept  in  its  normal  position,  and  the  centers  are  not 
more  likely  to  wear  out  of  true  than  when  turning  straight  work.  In 
either  of  these  methods  of  taper-turning  it  is  necessary  that  the  two 
lathe-centers  be  of  the  same  height,  otherwise  the  sides  of  the  taper 
will  not  be  straight  lines.  The  point  of  the  tool  should  be  set  to  the 
same  height  as  the  point  of  the  center. 

As  stated  in  Chapter  XV,  the  workman  should  turn  the  lathe  through 
one  revolution  and  be  sure  that  the  tail  of  the  dog  clears  the  sides  and 
bottom  of  the  slot  in  the  face-plate.  The  tail  of  the  dog  should  be  oiled, 
as  should  also  the  points  of  both  centers. 

In  fitting  a  taper-shaft  to  its  enveloping  element,  which  for  con- 
venience we  shall  call  a  collar,  the  collar  is  usually  finished  first.  There- 
fore chuck  and  bore  the  collar,  using  either  the  compound  rest  or  the 
taper  attachment  for  roughing  it  out.  If  the  lathe  has  no  taper  attach- 
ment, the  compound  rest  may  be  used  when  the  depth  of  the  hole  is  not 
greater  than  3  to  4  inches.  The  angle  corresponding  to  any  given  taper 
per  foot  may  be  computed,  or  the  rest  may  be  adjusted  by  a  gage,  or  it 
may  be  set  by  the  cut-and-try  method.  For  further  instructions  on 
making  taper-holes  see  Chapter  X. 

To  taper  the  shaft  by  setting  the  tail-stock  over,  the  latter  may  be 
adjusted  approximately  in  accordance  with  the  principles  already  out- 
lined. To  make  the  slight  correction  necessary,  proceed  as  follows: 
with  the  square-nose  tool  turn  a  place  at  each  end  of  the  taper  about 
Vie"  wide  and  about  1/32//  larger  than  the  final  diameter.  Feed  the 
square-nose  tool  outward  about  an  inch,  and  then  feed  it  toward 
the  work  again  until  a  6"  scale  will  just  enter  between  the  point  of 
the  tool  and  the  last  turned  place.  Move  the  carriage  to  bring  the 
tool  in  line  with  the  first  turned  place  and  test  in  a  similar  manner.  If 
not  correctly  alined,  readjust  the  tail-stock  and  proceed  in  the  same 
manner  until  the  6"  scale  will  fit  equally  well  between  the  point  of  the 
tool  and  the  work  at  the  two  grooves.  The  shaft  may  be*  next  turned  to 
the  diameter  of  these  grooves  and  tried  in  the  collar.  If  it  shakes  per- 
ceptibly, readjust  the  tail-stock  and  take  another  cut.  The  next  time 
it  is  tried  it  should  very  nearly  fit,  and  before  placing  the  collar  on 
the  shaft  this  time,  the  shaft  should  be  given  three  marks  with  chalk 
(Prussian  blue  would  be  better)  the  full  length  of  the  taper,  and  about 
equally  divided  around  the  periphery.  By  moving  the  collar  around  on 
the  shaft  its  contact  will  be  indicated  by  the  rubbing  off  of  the  chalk. 
The  shaft  should  be  rotated  in  the  lathe  and  filed  where  the  chalk  is 
rubbed  off  until  the  bearing  is  satisfactory. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK  267 

It  should  be  unnecessary  to  give  any  further  instructions  respecting 
the  use  of  the  taper  attachment.  The  method  of  testing  the  fit  of  the 
work  may  be  exactly  the  same  as  when  turning  tapers  by  setting  over 
the  tail-stock.  It  may  be  welito  explain  that  the  provision  for  adjust- 
ment of  the  tail-stock  will  not  admit  of  turning  a  taper  of  as  great  a 
degree  of  angularity  as  may  be  turned  with  the  taper  attachment. 

The  Steady  Rest,  Cathead,  etc. — The  steady  rest  is  shown  at  R  2 
in  Fig.  214.  This  device  is  used  for  supporting  a  slender  shaft  near  the 
middle  to  prevent  the  shaft  from  springing  away  from  the  cutting-tool. 
It  is  also  used  to  support  a  shaft  at  the  end  when  it  is  necessary  to  per- 
form some  operation  on  the  end  of  the  shaft  that  cannot  be  done  with  the 
tail-stock  in  position.  In  the  latter  case  the  tail-stock  is  moved  to  the 
right,  and  while  the  work  is  supported  on  one  end  by  the  steady  rest,  the 
other  end  is  held  either  by  the  chuck,  or  by  a  strap  which  holds  the  work 
in  contact  with  the  lathe-center.  Fig.  385,  which  is  taken  from  "Machin- 


FIG.  385. 

ery,"  shows  a  lathe-spindle  supported  as  last  described.  In  this  case 
the  spindle  is  driven  by  the  lathe-dog  in  the  usual  manner,  and  it  is 
held  to  the  center  by  bolts  and  a  strap  called  a  "  hold-back,"  the  pressure 
of  which  is  sustained  by  the  dog. 

Whether  the  steady  rest  be  placed  at  the  end  of  the  work  or  near  the 
middle,  there  must  be  a  true  bearing  on  the  shaft  where  it  revolves  in 
the  rest.  If  the  shaft  is  not  too  slender,  the  bearing  near  the  middle 
may  be  turned  on  the  centers  in  the  usual  manner  by  taking  very  light 


268 


MACHINE-SHOP  TOOLS  AND  METHODS 


cuts.  It  is  generally  better,  however,  to  use  a  cathead.  The  latter  is 
a  kind  of  cylindrical  shell  having  a  truly  turned  bearing  designed  to  run 
in  the  steady  rest.  It  is  held  on  the  shaft  by  three  or  four  set-screws  at 
each  end  of  the  shell.  Fig.  386  shows  a  cathead  held  on  a  shaft  as  indi- 


FIG.  386. 

cated.  The  cathead  is  adjusted  by  the  set-screws  until  it  runs  "true," 
on  the  same  principle  that  work  is  adjusted  in  a  chuck.  The  illustration 
shows  the  Bath  indicator  as  used  for  this  purpose.  In  the  absence  of 
such  an  instrument,  the  cathead  may  be  adjusted  in  connection  with 
a  common  lathe  tool  held  in  the  tool-post.  The  lathe  could  be  turned 
backwards  to  avoid  having  the  cathead  cut  by  the  tool.  Or,  better  still, 
a  piece  of  hardwood  could  be  shaped  to  take  the  place  of  the  tool. 

Some  prefer  to  set  the  cathead  by  giving  it  a  light  coat  of  red  lead 
and  marking  the  revolving  head  by  a  pencil  held  in  the  hand.  Special 
care  is  required  in  adjusting  the  steady  rest,  either  with  or  without  the 
cathead,  as  it  is  very  easy,  by  screwing  one  of  the  lugs  up  too  far,  to 
deflect  the  work.  It  is  usually  best  to  adjust  the  lugs  while  the  work 
is  revolving. 

Turning  a  Cathead. — The  cathead  should  be  made  quite  strong, 
otherwise  it  will  be  sprung  out  of  shape  while  it  is  being  adjusted  on 
the  shaft.  It  should  also  be  turned  very  carefully.  For  this  purpose 
it  may  be  placed  on  a  stout  arbor  and  adjusted  by  set-screws.  After 
taking  a  roughing  cut,  the  pressure  of  the  set-screws  should  be  relieved 
before  the  finishing  cut  is  taken.  The  cathead  need  not  be  finished 
on  the  inside. 

The  Follower-rest. — In  some  cases  the  work  is  so  frail  that  it  is 
necessary  to  support  the  pressure  of  the  cut  by  a  device  bolted  to  the 
carriage.  This  device,  which  is  shown  in  Fig.  387,  is  placed  nearly 
opposite  the  tool  and  travels  with  it.  In  using  the  follower-rest  the 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


269 


shaft  is  first  turned  a  few  inches  at  the  end  to  give  a  true  bearing  for 
the  rest.  The  rest  is  next  placed  in  position  and  its  lugs  adjusted  in 
contact  with  the  shaft,  when  jjjie  cut  may  be  continued.  Sometimes 
the  shaft  is  turned  to  fhe  finished  size  at  the  end  and  two  tools  are  used 


FIG.  387. 


FIG.  388. 


in  advance  of  the  follower-rest,  the  forward  being  a  roughing-tool  and 
the  rear  one  a  finishing- tool.  With  this  arrangement  one  traverse  of 
the  tools  finishes  the  shaft. 

The  follower-rest  is  often  made  in  a  form  which  requires  a  bushing 
for  each  size  of  shaft.  Fig.  388  shows  the  Reed  follower-rest,  which 
is  so  designed  that  either  bushings  or  adjustable  lugs  may  be  used. 
The  illustration  shows  a  bushing  secured  to  the  rest. 

Machining  a  Small  Cast-iron  Crank. — For  machining  a  cast-iron 
crank  of  the  dimensions  given  in  Figs.  389  and  390,  the  crank  might  be 
cast  with  flanges  as  in  Fig.  391,  and  the  machine  operations  could 
be  as  follows: 

(1)  Center  at  A  and  B  and  face  ends  to  length. 


270 


MACHINE-SHOP  TOOLS  AND  METHODS 


(2)  Turn  the  four  disks  to  2l/4". 

(3)  Draw  a  line  on  flanges  with  key-seat  rule  as  in  Fig.  392. 


f 

* 

t 

% 

i 

t 

1 

i 

^ 
1 

' 

f 

% 

i 
i 

_j^  > 

«  —  .^..^ 

i 

<  \y^-  » 

-*•/'-- 

Crank        One  C.I.  Finish  all  ovgfc 

FIG.  389. 


FIG.  390. 


(4)  Draw  radial  lines  joining  latter  line  with  centers  A  and  B. 

(5)  With  hermaphrodite  set  to  l/2",  draw  arcs  intersecting  the  radial 
lines  as  at  C,  Fig.  392. 


Key-Seat  Rule 


G 

E 

F 

-H            | 

<-^A 

J— 

<--  —  L  > 

—  K 

11 


FIG.  391. 


FIG.  392. 


(6)  Drill  and  ream  centers  C  and  Z),  taking  care  to  keep  the  centers 
from  "running." 

(7)  Next  rough  out  crank  at  E,  F,  J,  K,  to  within  r/32//  of  size. 

(8)  Turn  to  final  dimensions  and  polish  at  G,  H,  I. 

(9)  Turn  the  two  end  disks  to  diameter  of  E. 

(10)  Finish  and  polish  at  E,  F,  J,  K. 

Precaution. — While  turning  E  and  F  the  crank  should  be  supported 
at  L  by  a  small  rod  or  by  a  screw  with  nut  on  end.  The  rod  or  screw 
must  not  be  forced  but  pressed  in  lightly  with  the  fingers  to  avoid  spring- 
ing the  casting.  When  running  the  lathe  fast  for  work  of  this  character 
a  weight  (of  any  kind)  should  be  bolted  to  the  face-plate  of  the  lathe 
to  counterbalance  the  work. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


271 


Machining   a   Paper-weight. — Fig.  393  shows   a  paper-weight  the 
base  of  which  is  brass  and  the  stem  steel.     Figs.  394  and  395  show 


I I 


FIG.  393. 


FIG.  394. 


FIG.  395. 


the  two  parts  in  detail.     To  make  this  paper-weight,  we  would  com- 
mence with  a  rough  casting  of  Fig.  394  and  proceed  as  follows: 

(1)  Chuck  casting  and  rough   off  face  A  with  the  tool  shown  in 
Fig.  290,  finishing  and  polishing  at  A. 

(2)  Bore  out  the  cored  hole  to  within  a  few  thousandths  of  an  inch 
with  a  common  boring-tool,  which  must  not  have  rake,  and  finish  with 
reamer.      With  lathe  rotating,  remove  the  sharp  outer  corner  of   the 
hole  with  a  scraper  or  otherwise. 

(3)  Place  on  arbor  and  machine  B,  C,  D  to  dimensions,  using  tools 
Figs.  290  and  291.     A  semicircular  scraper  may  be  used  for  the  fillet 
as  shown  in  Figs.  97  and  98,  and  the  exterior  curved  surface  may  be 
smoothed  by  a  square-end  scraper. 

(4)  Polish,  first  using  file,  then '  fine  emery-cloth,  and  finally  rouge- 
cloth  or   clean  dry  waste  and  fine  emery.     See  also  methods  of  polish- 
ing in  Chapter  XXIX. 

For  Fig.  395  proceed  as  follows: 

(5)  Saw  off  a  piece  of  15/i6r/  round  machine  steel  3l/±"  long. 

(6)  Center,  face  ends,  and  rough  to  29/32"  diameter. 

(7)  Machine  tail-stock  end  (including  H),  making  0  smaller  than  G. 
G  must  be  made  .0005"  larger  than  the  hole  in  Fig.  394  for  a  force  fit. 


272 


MACHINE-SHOP  TOOLS  AND  METHODS 


(8)  Reverse  and  machine  other  end  to  9/i6r/- 

(9)  Turn  K,  M,  N ',  using  preferably  a  forming-tool  *  for  the  spherical 
part.     Finish  and  polish  with  file  and  emery-cloth  and  knurl  as  shown. 

(10)  File  and  polish  hexagon  (l/2ff  across  flats). 

(11)  Cut  off  0  and  P,  and  finish  and  polish  extreme  end  of  N.    The 
piece  may  be  held  in  a  chuck  (preferably  a  draw-in  chuck)  when  finish- 
ing the  extreme  end  of  N',  and  a  concave  side-tool  or  a  scraper  may  be 
used  to  precede  the  emery-cloth. 

(12)  Press  stem  into  base,  protecting  ends  with  Babbitt  metal  or 
otherwise.     An  arbor-press  or  strong  drill-press  may  be  used  to  press 
in  the  stem. 

Special  Method  of  Machining  a  Cone  Pulley. — As  indicated  in  the 
chapter  on  turret-lathes,  when  work  is  machined  in  the  engine-lathe 


FIG.  396. 

without  special  tools  and  fixtures  the  processes  are  comparatively  slow. 
In  contrast  with  these  slow  processes  the  attention  of  the  reader  is 
called  to  the  method  of  machining  a  cone  pulley,  illustrated  in  Figs.  396 
and  397.  In  the  first  figure  several  tools  are  shown  in  operation  on 
the  steps  of  a  cone  pulley,  these  tools  being  held  in  a  special  tool-holder. 


of 


*  A  good  article  on  making  forming-tools  was  published  in  the  shop  edition 
'Machinery/'  June,  1904,  page  339. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


273 


The  sizes  for  the  various  steps  are  determined  by  adjusting  the  tools 
to  the  stepped  gage  held  on  the  .tail-spindle.      In  Fig.  397  the  internal 


FIG.  397. 

diameters  of  the  cone  pulley  are  bored  simultaneously  by  the  multiple 
cutter-head  shown. 

The  construction  of  the  split  chuck  used  for  gripping  the  pulley  is 
worthy  of  note.  Special  chucks  secured  in  this  manner  to  the  face-plate 
are  usually  centered  by  having  a  tongue  or  ledge  on  the  chuck  fit  a 
corresponding  recess  turned  in  the  face-plate.  In  some  cases  dowel- 
pins  passing  through  the  face-plate  and  chuck-ears  are  used  instead. 
Any  machining  that  is  required  in  the  inside  of  the  chuck  is  always 
reserved  until  after  the  chuck  has  been  fitted  to  the  face-plate.  In 
many  cases  it  is  preferable  to  make  such  chucks  to  screw  directly  on 
the  lathe-spindle. 

In  machining  a  cone  pulley  the  casting  must  pass  through  a  number 
of  different  processes  before  it  is  completed.  The  two  illustrations 
given  are  from  an  article  by  C.  F.  Pease  in  the  "  American  Machinist/' 
vol.  27,  pages  613  and  614,  showing  the  method  followed  by  the 
Lodge  &  Shipley  Company.  The  reader  is  referred  to  this  article  for 
further  information  on  the  subject. 

Turning  Curved  Shapes. — Figs.  398  and  399  show  two  views  of  a 
ball-turning  rest  which  is  used  interchangeably  with  an  ordinary  tool- 


274 


MACHINE-SHOP  TOOLS  AND  METHODS 


rest.     In  using  this  rest  the  lower  slide  is  locked  to  the  carriage  and 
the  cross-feed  mechanism  set  in  motion.     As  the  cross-feed  screw  passes 


FIG.  398. 

through  the  nut  seen  secured  to  the  rack  in  the  inverted  view,  the 
rotation  of  the  screw  causes  longitudinal  motion  of  the  rack,  and  this  in 
turn  causes  rotation  of  the  rest  by  the  gearing  shown. 


FIG.  399. 


Figs.  400  and  401  show  respectively  a  side  view  and  an  end  view 
of  a  ball-turning  attachment  which  may  be  bolted  on  top  of  a  tool-rest 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK 


275 


in  place  of  the  tool-post.     This  device  consists  of  the  main  casting 
shown,  in  which  is  journaled  a  "shaft  having  at  its  left  end  a  slotted 


FIG.  400. 

arm  and  a  tool-post.     The  tool-post  is  held  in  the  slotted  arm  by  the 
top  screw,  the  tool  being  held  in  the  tool-post,  as  will  be  clearly  under- 


FIG.  401. 

•stood  from  the  illustration.  The  disk-shaped  casting,  secured  to  the 
right  end  of  the  shaft  by  a  key  and  the  nut,  may  be  either  a  spur-gear, 
driven  by  the  gearing  in  the  lathe-apron,  or  it  may  be  a  worm-gear 
operated  by  worm  and  handle.  The  illustration  does  not  show  the 
means  for  operating  the  device. 

Ball-turning  attachments  may  be  used  for  turning  work  between 


276 


MACHINE-SHOP  TOOLS   AND  METHODS 


centers,  such  as  the  ball  handles  used  on  lathes.      They  may  also  be 
used  for  turning  a  ball  on  the  end  of  a  bar  held  in  the  chuck. 

Other  Methods  of  Turning  Balls. — In  the  absence  of  any  special 
attachment,  balls  are  sometimes  roughed  out  approximately  right  with 

a  lathe-tool,  and  finished  to  a  tem- 
plate by  a  common  scraper.  Fig.  402 
shows  a  special  scraper  consisting  of 
a  bar  of  tool  steel  having  a  hole 
drilled  in  the  end,  and  having  its 
FIG.  402.  corner  beveled  to  form  a  cutting- 

edge.     In  using  the  scraper  the  ball 

is  first  roughed  out  with  a  lathe-tool.     The  scraper  is  then  pressed 
against  the  revolving  ball,  when  it  finds  its  own  center  and  gives  the 


FIG.  403. 

ball  the  spherical  shape,  regardless  (within  limits)  of  the  diameter  of 
hole  in  the  tool.  Balls  may  also  be  shaped  by  a  lathe-tool,  the  end 
of  which  is  made  to  the  same  form  as  the  ball. 


SOME  EXAMPLES  OF  ENGINE-LATHE  WORK  277 

Turning  Curved  Shapes  with  Guiding  Forms. — A  great  variety  of 
curved  shapes  may  be  turned  in  connection  with  forms.  Fig.  403  *  shows, 
secured  to  the  face-plate,  a  piece,  of  work  which  is  to  be  turned  to  a 
radius  of  20".  A  form  B  of  the  required  shape  is  secured  to  a  common 
angle  plate,  the  latter  being  bolted  to  the  lathe-bed.  With  a  guiding 
roller  E,  journaled  in  a  bracket  on  the  rest,  and  a  spring  or  weight 
tending  to  hold  the  roller  in  contact  with  the  form,  the  cross-feed  of 
the  lathe  is  set  in  motion,  when  the  tool  will  be  forced  to  follow  the 
required  path.  If  a  weight  be  used,  it  may  be  suspended  by  a  rope 
attached  to  the  lathe-carriage  and  running  over  a  roller  secured  to 
the  lathe-bed.  When  doing  this  work  the  feed-screw  of  the  upper  rest 
must  be  removed,  and  the  carriage  should  be  clamped  to  the  lathe-bed. 

Sometimes  the  work  is  of  such  a  character  as  to  require  that  the 
guiding  form  be  held  on  the  back  side  of  the  lathe-bed.  In  this  case 
the  guiding  roller  and  rope  are  attached  to  the  cross-slide,  and  the  weight 
is  suspended  over  a  roller  at  the  back  side  of  the  lathe.  In  shaping 
such  work  the  cross-feed  screw,  or  the  nut  for  the  same,  must  be  removed 
and  the  carriage  be  fed  longitudinally.  Irregularly  curved  handles 
may  be  formed  in  this  way.  It  should  be  understood  that  the  shape 
turned  with  a  pointed  tool  is  not  an  exact  duplicate  of  the  form. 

In  accordance  with  the  principle  outlined,  cams  may  be  made  in 
the  engine-lathe.  In  doing  such  work,  the  cam  blank  and  form  are 
usually  secured  on  an  arbor,  the  latter  being  driven  between  lathe-centers 
in  the  usual  manner.  A  revolving  milling-cutter  of  the  same  diameter 
as  the  roller  gives  better  results  than  a  pointed  tool.  This  arrangement, 
however,  is  more  elaborate,  as  it  requires  a  counter-shaft  or  other  means 
for  rotating  the  milling-cutter.  The  milling-cutter  could  be  secured  to 
a  spindle  running  in  a  bracket  held  on  the  tool-rest. 

Further  instructions  respecting  lathe  work  are  given  in  connection 
with  the  next  chapter,  and  in  the  chapters  on  boring  bars,  etc. 

*  Cut  first  used  in  connection  with  an  article  by  J.  Wheeler  in  "American 
Machinist,"  vol.  27,  page  557. 


CHAPTER  XVIII 
THREAD-CUTTING  IN  THE  ENGINE-LATHE 

Meaning  of  the  Terms  "  Pitch,"  "  Lead,"  etc. — In  transmitting  power 
by  belting  there  is  generally  a  slight  irregularity  due  to  the  slip  of  the 
belt.  This  is  of  no  consequence  in  the  ordinary  feeding  of  the  lathe- 
carriage,  and  the  belt  and  pulleys  are  sufficiently  accurate;  but  as  stated 
hi  the  chapter  on  Lathes,  the  mechanism  used  in  moving  the  carriage 
for  thread-cutting  must  be  positive  and  accurate.  In  the  chapter  referred 
to,  brief  allusion  was  made  to  the  method  of  cutting  threads.  In  this 
chapter  the  subject  will  be  further  considered. 

Imagine  a  rod  held  between  the  lathe-centers  and  caused  to  revolve 
with  the  spindle.  If  now  a  pointed  tool  held  in  the  tool-post  of  the 
lathe  be  fed  against  the  revolving  rod,  and  the  lathe-carriage  be  caused 
by  the  gearing  to  traverse  the  lathe-bed,  the  tool  will  cut  a  helical 
groove.  This  operation  is  called  thread-cutting.  The  coarseness  of  a 
thread,  or  the  distance  that  the  carriage  advances  for  each  revolution  of 
the  rod,  may  be  changed  by  changing  the  ratio  of  the  gears  which  move 
the  carriage.  There  is  some  confusion  respecting  the  terms  used  to 
denote  the  coarseness  of  a  thread,  and  it  will  be  necessary  to  define 
these  terms  before  proceeding  further.  The  term  lead,  as  used  in  the 
machine-shop,  means  the  distance  that  a  screw  turning  in  a  nut  will 
advance  in  one  revolution,  or  (as  applied  to  a  "  lead-screw  ")  the  dis- 
tance that  the  lathe-carriage  is  moved  by  one  revolution  of  the  lead- 
screw.  The  term  pitch  is  used  variously  to  indicate,  first,  the  lead; 
second,  the  number  of  threads  per  inch,  and  third,  the  distance  between 
the  centers  of  two  adjacent  threads.  The  latter  definition  will  be  the 
one  used  in  this  work.  If  we  wind  a  bit  of  sewing-thread  helically 
around  a  rod  so  that  the  thread  advances  l/±"  in  going  once  around  > 
we  shall  have  a  good  illustration  of  a  single-thread  screw  of  l/±"  lead. 
The  pitch  is  also  1/4f.  Thus  the  pitch  and  lead  are  equal  in  a  single- 
thread  screw.  Now  if  we  wind  another  thread  around  the  rod  so  that 
its  helix  shall  describe  a  line  centrally  between  the  helical  lines  of  the 

278 


THREAD-CUTTING  IN  THE  ENGINE-LATHE 


279 


FlG-  404- 


first  thread,  the  two  threads  together  will  illustrate  a  double-thread  screw. 

But  the  pitch  of  the  screw  is  changed  to  1/8",  while   the  lead  remains 

1/4//  as  before.     In  Fig.  404  we  start 

at    the    right    with    a  -single-thread 

screw  of  P^/g",  and  then  cut  an- 

other   thread,    when    P  =  l/4".      We 

may  have   any   number   of   threads, 

but  we  seldom  cut  other  than  single, 

double,  triple,  and  quadruple  screws. 

The  expressions  "  threads  per 
inch"  and  "  turns  per  inch"  are  also 
used  in  connection  with  screw-cutting. 
As  some  lathe  lead-screws  have  double 
threads  the  first  term  is  misleading, 
and  as  a  substitute  for  the  latter  we 
shall  coin  the  more  convenient  word  "  inch-turns,"  meaning  the  number 
of  turns  a  screw  makes  in  a  nut  while  advancing  1",  or  while  moving 
the  nut  1". 

Computing  the  Change-gears.  —  The  diagram  in  Fig.  405  will  be 
used  with  the  formulas  for  screw-cutting.  In  this  figure  c  is  the  gear 
on  spindle,  or  gear  on  stud,  as  it  is  sometimes  called,  d  the  intermediate, 
and  /  the  gear  on  lead-screw.  The  number  of  the  teeth  in  the  inter- 
mediate does  not  affect  the  ratio,  and  this  gear  is  not  considered.  In 
the  formulas  let  c  equal  the  number  of  teeth  in  stud-gear,  /  the  teeth 
in  lead-screw  gear,  L  the  inch-turns  of  lead-screw,  and  R  the  inch-turns 
of  the  required  screw.  Assuming  that  the  gears  which  transmit  motion 
to  the  stud  have  equal  numbers  of  teeth,  as  is  the  case  in  most  lathes, 
these  gears  will  not  affect  the  ratio.  For  convenience  we  shall  speak 
of  such  a  lathe  as  being  geared  one  to  one.  Assume  also  that  we  have 
the  following  list  of  change-gears:  20  teeth,  40  teeth,  46,  48,  80,  100. 
Now  let  it  be  required  to  cut  a  screw  of  l/±"  lead,  or  4  inch-  turns,  and 
let  the  lead-screw  also  be  l/±"  lead.  The  proportions  of  the  gears  will 
be  indicated  by  the  following  expression: 

Number  inch-turns  on  lead-screw  number  teeth  in  stud-gear 

Number  inch-turns  on  required  screw    number  teeth  in  lead-screw  gear' 

Then  by  formula  W  -B  =  -T  =  T'     ~r   then   is   the  ratio  of  teeth  in 
t\i      i       4       4 

stud-gear  to  teeth  in  lead-screw  gear.  Now  if  we  have  no  gears  with 
less  than  20  teeth  we  multiply  both  numerator  and  denominator  by  5 
and  we  have  20  teeth  in  each  of  these  gears  for  4  inch-turns,  or  1/4//  lead. 


280  MACHINE-SHOP  TOOLS  AND  METHODS 

The  greater  the  number  of  teeth  in  the  lead-screw  gear,  or  the  smaller 
the  number  of  teeth  in  the  stud-gear,  the  greater  will  be  the  number 
of  revolutions  of  the  required  screw  to  1"  travel  of  the  thread-tool. 
Therefore,  if  we  wish  to  cut  a  thread  of  l/8"  lead  or  8  inch-turns,  other 
conditions  remaining  the  same,  all  we  need  to  do  is  to  place  a  40-tooth 

gear  on  the  lead-screw.      Thus  by  formula  (1)    -—  =  —=^-.     In  other 

K      o       4U 

words  gears  of  equal  numbers  of  teeth  cut  screws  of  same  lead  as  the 
lead-screw,  while  doubling  the  number  of  teeth  in  lead-screw  gear 
doubles  the  inch-turns  of  required  screw,  etc. 

In  some  lathes  the  gears  are  not  one  to  one,  and  in  such  a  case  we 
must  ascertain  the  ratio  of  these  gears  and  use  this  ratio  in  the  formula. 
We  may  find  the  ratio  of  the  gears  by  marking  the  stud-gear  and  lathe 
face-plate  in  relation  to  fixed  points,  and  then  turning  the  lathe-spindle 
and  noting  revolutions  of  stud-gear  to  one  of  face-plate.  Assuming  b 
to  have  10  teeth  and  a  20  teeth,  and  lead-screw  same  as  before,  let  it  be 
required  to  cut  screws  of  4  inch-turns  or  V4"  lead.  Then  by  formula  (2) 

-        4XS   a  '    -..-'• 

a     c  20     8 


Multiplying  both  terms  by  5  as  before,  we  have 

8     5     40      stud-gear  teeth 
4     5     20     screw-gear  teeth  ' 

Again,  assume  a  lead-screw  of  6  inch-turns  and  let  it  be  required 
to  cut  a  screw  of  \\l/2  inch-turns,  then 


12       4     48          teeth  in  stud-gear 


R     ~  \\l/2     nl/2     4     46     teeth  in  lead-screw  gear' 


Compound  Gearing.— The  system  of  gearing  shown  in  Fig.  405  is 
called  simple  or  single  gearing,  because  there  is  only  one  gear  on  the 
intermediate  shaft,  and  as  has  been  intimated,  this  does  not  affect  the 
velocity  ratio  of  the  stud-  and  screw-gears.  Some  lathes  have  several 
intermediate  gears  in  the  same  vertical  plane,  the  stud-gear  being  placed 
on  the  outer  end  of  the  main  spindle.  This  arrangement  gives  the 
same  results  as  the  one  intermediate.  But  when  there  are  two  inter- 
mediates of  different  diameters  on  the  same  shaft,  then  we  have  com- 


THREAD-CUTTING  IN  THE  ENGINE-LATHE 


281 


pound  gearing,  and  the  intermediate  gears  must  be  taken  into  account 
in  the  calculation. 

Some  lathes  are  so  designed  that  a  wide  range  of  inch-turns  cannot 
be  obtained  by  single  gearing.    j,n  such  a  lathe  both  single  and  com- 


FIG.  405 


T^  =  Inch-turns  on  required  screw. 

FIG.  405. 


L  =  Same  on  lead  screw. 

FIG.  406. 


pound  gearing  are  used.  Fig.  406  shows  a  diagram  applicable  to  com- 
pound gearing,  and  formula  (3)  has  been  prepared  for  use  with  this 
diagram.  Formula  (3): 


ce 

x   or 


ace 

+=     OT 


Let  it  be  required  to  cut  a  screw  of  say  40  inch-turns  in  a  lathe 
having  a  lead-screw  of  l/±"  lead,  or  4  inch-turns,  and  having  gears  a 
and  b  1  to  1.  If  we  compute  by  formula  (1)  we  shall  have, 

L  _c  __  4  =  20 
R  ~f  ~40~200* 

These  are  the  proportions  of  the  gears  that  could  be  used  by  single 
gearing,  but  we  have  no  gear  of  200  teeth.  If  we  select  40  and  80  for  c 
and  d  respectively,  the  proportions  of  the  mating  gears  at  e  and  /  may 


be  found  as  indicated  hi  formula   (3)   by  dividing  — -  by  — . 

<iUU  oU 

20       1         ,40111122 

__      f\  -r\/~i      __  __  •        _• v>/  

200     10  80     2'    10' 2  ~10X1  ~10V 


Thus 


282  MACHINE-SHOP  TOOLS  AND  METHODS 

In  looking  through  our  list  of  gears  we  find  20  and  100,  which  may  be 

2 
used  for  the  proportion  —  .     Substituting  these  values  in  the  formula 

we  have, 

4X^ 
11^40      20  =1_1JL 

40      80     100     25      10' 

Metric  and  Fractional  Threads.  —  It  sometimes  happens  that  we 
have  to  cut  a  metric  screw  on  an  ordinary  American  la,the.  For  this 
purpose  we  need  one  gear  having  127  teeth;  this  is  called  a  "translating" 
gear.  It  is  found  as  follows:  1000  millimetres  =  1  metre  =39.37"  in 
length.  lOOO-i-39.37  =25.40005=  millimetres  in  I".  Therefore  to  cut  a 
screw  of  1  millimetre  lead  (  =25.4  inch-turns)  in  a  lathe  geared  1  to  1  and 

with  lead-screw  =  4  inch-turns,  we  have  by  formula  (1)  H^-rX^-  =r^  =-7-. 

ZO.4      o       iZt       f 

We  cannot  use  any  smaller  gear  than  127  because  no  smaller  number 
is  divisible  by  25.4  without  a  remainder.  The  gear  on  stud  will,  of 
course,  depend  on  the  inch-turns  of  lead-screw,  but  whatever  number 
of  teeth  it  may  have  we  should  multiply  that  number  by  2  for  a  screw 
having  2  millimetres  lead,  by  4  for  4  millimetres  lead,  etc.  This  can 
be  proved  by  the  formula  as  follows.  Assuming  a  lead-screw  of  4 
inch-turns,  let  it  be  required  to  compute  change-gears  for  1,  2,  and  4 
millimetres. 

r  l  millimetre  lead' 


=.  «      «2 

R      25.4-210     127 

L    _l_v^=-52.        »    «4 

R     25.4-4    20     127 

The  simple  formulas  and  methods  here  outlined  involve  the  principles 
common  to  all  gearing  computation  in  which  velocity  ratios  are  con- 
cerned. The  methods  used  in  computing  change-gears  for  metric  threads 
will  apply  equally  well  to  fractional  threads.  By  substituting  diameters 
for  numbers  of  teeth  in  the  formulas,  they  may  also  be  applied  to  belt 
and  pulley  transmission.  The  student  should  study  these  principles 
in  connection  with  the  machines  in  the  shop  until  he  thoroughly  under- 
stands them. 


THREAD-CUTTING  IN  THE  ENGINE-LATHE 


283 


Cutting  a  Fractional  Thread  with  Change-gears  of  Approximately 
Correct  Proportions. — It  is  possible  to  cut  a  fractional  thread  on  a 
parallel  shaft  with  gears  which*  vary  slightly  from  correct  proportions. 
This  may  be  effected  by  getting  life  tail-stock  over  to  give  the  necessary 
variation  from  the  formula  results,  and  then  adjusting  the  taper  attach- 
ment to  make  the  tool  follow  the  parallel  side  of  the  shaft.  The  amount 
to  set  the  tail-stock  over  can  be  computed  very  closely.  Special  care, 
however,  is  required  to  so  arrange  the  contact  between  the  lathe-dog 
and  face-plate  as  to  prevent  a  variable  motion  being  imparted  to  the 
work.  This  method  is  sometimes  employed  in  threading  taps  to  com- 
pensate for  the  change  in  lead  caused  in  the  tempering  process.  For 
a  full  discussion  of  this  method  see  " American  Machinist"  of  April  3, 
1902  page  479,  and  the  January,  1904,  number  of  "  Machinery,"  page 
273,  regular  edition. 

Methods  of  Setting  Thread-tools.— The  United  States  standard  and 
V-thread  tools  should  be  so  set,  in  relation  to  the  work,  that  a  line  bisect- 


_i 


FIG.  407. 


ing  the  angle  formed  by  the  two  cutting-edges  of  the  tool  shall  be  at 
right  angles  to  the  axis  of  the  work.  Figs.  407,  408,  and  409  show  the 
methods  of  setting  these  tools.  Fig.  407  is  the  simplest  case.  In  this 
figure  we  have  a  cylinder  of  uniform  diameter  upon  which  it  is  required 
to  cut  V  threads.  The  cylinder  is,  of  course,  adjusted  with  its  axis 
parallel  to  the  lathe-shears,  and  the  gage  C  has  the  60°  V  groove  so 
formed  in  relation  to  its  parallel  sides  as  to  conform  to  the  conditions 
above  expressed  respecting  the  point  of  the  lathe-tool.  It  is  obvious 
then  that,  if  the  tool  be  adjusted  to  correspond  with  the  groove  in  C, 
the  latter  being  held  against  the  side  of  the  cylinder  as  shown,  the  tool 
will  be  properly  adjusted  in  relation  to  the  work.  Fig.  408,  which 


284 


MACHINE-SHOP  TOOLS  AND  METHODS 


shows  the  same  principle  applied  to  internal  work,  will  be  sufficiently 
clear  without  further  explanation. 


\ 


111 


A 


C=  Centre  Gauge 


FIG.  408. 

Fig.  409  shows  the  method  of  setting  the  tool  for  a  tapering  screw. 
In  this  case  it  will  not  do  to  use  the  gage  against  the  side  of  the  blank, 


Axis  of  lathe  spindle 
~Axfs~6f  blan'k 


FIG.  409. 

because  the  sides  are  not  parallel  with  the  axis.  But  if  the  side  of  the 
gage  be  pressed  against  the  true  end  of  the  blank,  and  the  tool  be  adjusted 
so  that  one  of  its  edges  coincides  with  the  side  of  the  gage  as  shown, 
the  thread  will  be  normal  to  the  axis  of  the  screw,  as  required.  This 
method  will  apply  whether  the  taper  of  the  thread  be  made  by  the 
taper  attachment  or  by  setting  the  tail-stock  over.  The  former  is  the 
more  accurate  method. 


THREAD-CUTTING  IN  THE  ENGINE-LATHE 


285 


The  lead  of  all  threads,  including  taper  threads,  should  be  measured 
parallel  with  the  axis  of  the  screw. 

The  gage  C  will  not^  answer  fer  other  threads  than  V  and  the  United 
States  standard,  but  simple  gages  may  be  made  on  the  same  principle 
for  other  threads. 

Some  Precautions  and  Principles  in  Connection  with  Thread-cutting. 
—Fig.  410  shows  a  short  shaft  upon  which  three  different  leads  of  U.  S. 


FIG.  410. 

standard  threads  are  required.  The  threads,  which  are  represented  by 
the  conventional  method,  are  13,  11,  and  10  inch-turns  respectively  for 
the  V2-,  5/8-,  and  3/4-inch  diameters.  We  shall  not  give  in  detail  the 
order  of  operations  for  this  work,  except  to  state  that  the  blank  is  turned 
completely  to  the  dimensions  of  the  drawing  before  the  thread-cutting  is 
begun.  The  numbered  paragraphs  state  principles  applicable  to  Fig. 
410  and  to  thread-cutting  in  general.  It  is  more  difficult  to  do  smooth 
thread-cutting  than  smooth  turning  on  a  plain  cylinder.  To  insure  good 
work  careful  attention  must  be  given  to  the  following  instructions. 

(1)  It  is  preferable  to  have  one  tool  for  roughing  and  one  for  finishing 
the  thread.     The  finishing-tool  should  be  ground  and  oil-stoned  with 
special  care. 

(2)  To  get  the  most  accurate  shape  of  thread,  the  top  of  the  tools 
should  be  ground  flat  and  set  even,  horizontally,  with  the  point  of  the 
lathe-center,  as  shown  in  Fig.  411. 

However,  in  ordinary  work,  to  make 
the  tool  peel  the  metal  more 
smoothly,  it  may  be  permissible 
to  give  the  roughing-tool  a  slight 
degree  of  top  rake. 

(3)  The  tool  must  be  so  ground  FlG 
as    to    have    approximately    equal 

clearance  on  each  side  in  the  thread.     When  thus  ground  it  will  (in 


286  MACHINE-SHOP  TOOLS  AND  METHODS 

effect)  lean  toward  the  left  in  right-hand  thread,  and  toward  the  right 
in  left-hand  thread.  This  side  clearance  of  the  tool  must  extend  to  the 
extreme  top  edge.  Beginners  are  very  likely  to  leave  about  */64  or 
l/32  inch  at  the  top  edge  without  side  clearance  and  then  wonder  why 
the  tool  does  not  cut. 

(4)  The  tool  must  not  project  farther  than  necessary  from  the  tool- 
post,  and  the  tail-spindle  must  not  be  screwed  out  from  the  tail-stock 
more  than  sufficient  to  give  ample  clearance  of  lathe-carriage.     This 
latter  point  should  be  provided  for  before  starting  to  cut  the  thread; 
otherwise,  in  reversing  the  lathe  the  carriage  may  be  forced  against 
the  tail-stock  and  strain  the  mechanism  in  the  lathe-apron. 

(5)  To  avoid  marring  the  finished  surface,  leave  the  blank  about 
Vie"  larger  at  A  than  drawing  until  the  thread-cutting  is  done.     To 
finish  this  end,  use  a  special  screw-dog  as  in  Fig.  337,  or  screw  a  1/2"  nut, 
split  on  one  side,  on  B  and  drive  the  blank  by  a  lathe-dog  on  the  nut. 

(6)  If   the   lathe   has  a  compound  rest,  the  upper  slide  should  be 
turned  about  30°  in  the  direction  of  the  tail-stock.     If  then  the  tool  be 
taken  out  for  grinding,  it  may  be  adjusted  to  the  thread  by  movement 
of  the  upper  rest.     If  a  lathe  having  no  compound  rest  be  used,  the 
tool  may  be  adjusted  laterally  by  disengaging  the  reversing  gears,  pulling 
the  spindle  around  by  hand  until  the  thread  is  in  line  with  the  tool  and 
then  reengaging  the  gears.     Some  mechanics,  in  cutting  60°  thread, 
prefer  to  set  the  upper  or  compound  rest  at  30°  and  feed  the  tools  toward 
the  thread  by  this  rest,  using  first  a  roughing  thread-tool  and  then  two 
finishing-tools,  one  for  each  side  of  the  thread.    These  tools  are  given 
rake  and,  when  cutting  on  one  side  only,  they  cut  without  gouging.    See 
Fig.  412.* 

The  gibs  of  the  rests  must  be  snugly  adjusted  when  cutting  thread. 

(7)  In  taking  the  final  smoothing  cuts  on  the  thread,  if  the  tool 
does  not  respond  to  light  pressure,  it  is  an  indication  that  it  is  either 
dull,  or  has  insufficient  clearance,  or  is  defective  in  some  other  way. 
Under  such  conditions  the  tool  will  either  gouge  into  and  take  a  heavy 
cut,  making  a  rough  thread,  or  it  will  not  cut  at  all.     When  all  other 
conditions  are  right  the  failure  may  be  caused  by  a  low  temper  in  the 
tool.    To  avoid  spoiling  the  thread  the  difficulty  should  be  remedied 
before  proceeding  further. 

Use  of  the  Thread  Stop -gage. — Several  cuts  will  be  required  to  com- 
plete each  of  the  above  threads,  the  greatest  number  of    cuts  being 

*  Fig.  412  was  copied  from  a  cut    illustrating   an   article  by  "A  Mechanic" 
in  "  American  Machinist,"  July  31,  1890,  page  10. 


THREAD-CUTTING  IN  THE  ENGINE-LATHE 


287 


required  on  the  coarsest  lead.    The  depth  of  the  cut  is  determined  by 
the  judgment  of  the  workman,'  but  the  roughing  cuts  are,  of  course, 


FIG.  412. 

much  deeper  than  the  finishing  cuts.  Most  lathes  are  provided  with  a 
thread  stop-gage  like  that  shown  in  Fig.  231.  In  cutting  short  threads 
like  those  in  Fig.  410,  when  the  tool  reaches  the  end  of  the  thread  it 
is  quickly  withdrawn  by  the  cross-feed  handle  and  the  motion  of  the 
lathe  is  reversed.  During  the  backward  traverse  of  the  lathe-carriage, 
the  screw  S  of  the  stop-gage  is  adjusted  for  the  next  cut. 

Cutting  Square  Threads.  —  Fig.  413   shows  a  square-thread  screw 
and  nut  to  which  the  following  instructions  apply. 

(1)  Chuck  the   nut  and  face  outer  end  with  roughing-tool,  finishing 
with  side-tool. 

(2)  Turn  as  at  A  (Fig.  414)  with  centering-tool  (see  Fig.  376)  for  entry 
of  drill.     Drill  with  13/i6"  twist-drill,  finishing  to  7/8"  with  boring-tool 
and  reamer.     Counter-bore  as  at  B  (Fig.  415)  as  a  guide  for  gaging  depth 
of  thread. 

(3)  Rough  out  thread  with  tool  like  Fig.  416,  finishing  with  tool  full 
width  like  Fig.  417.     It  must  fit  a  nut-arbor,  which  may  also  answer  for 
a  gage.     A  tap  is  sometimes  used  to  size  the  nut-thread. 

(4)  To  turn  the  outside,  screw  nut  on  arbor  and  proceed  to  finish 
hi  the  same  manner  as  with  collar  referred  to  in  the  first  example  of 
lathe  work,  Chapter  XVII. 


288 


MACHINE-SHOP  TOOLS  AND  METHODS 


(5)  For  the  screw,  cut  off  1  Vie"  round  machine  steel  7  Vie"  long- 
Center  and  face  ends  to  length.  Turn  blank  to  1  Vs"  diameter  for  thread, 
leaving  it  larger  at  C. 


(6)  Before  cutting  the  thread,  read  again  the  instructions  given  in 
connection  with  Fig.  410. 

(7)  Rough  out  thread  with  outside  thread-tool   having  point  like 
Fig.  416,  and  finish  with  tool  having  point  full  width  like  Fig.  417,  testing 


THREAD-CUTTING  IN  THE  ENGINE-LATHE  289 

fit  by  a  gage  or  by  the  nut.     The  thread-tool  must  (in  effect)  lean  to 
the  left  and  have  clearance  to^extreme  edge  as  at  E,  Fig.  418. 

(8)  Polish  with  oil  and  emejy  on  soft-pine  stick.      Screw  thread 
end  into  threaded  driver  and  turn  and  polish  end  C. 


Round 
Corners 


About 
r*-3"  7'/ 
1  "32or64 


FIG.  416.  FIG.  417. 

(9)  In  connection  with  this  exercise  the  student  should  learn  to 
"catch  the  thread"  without  reversing  the  lathe.  To  do  this  stop  the 
lathe  just  before  the  tool  reaches  the  end  of  the  thread  and  turn  it  the 
remainder  of  the  way  by  hand,  bringing  it  to  rest  in  a  definite  position, 
which  should  be  noted  by  making  a  witness-mark  on  the  face-plate  in 
line  with  some  fixed  point  or  mark  about  the  lathe.  Now  disengage 
the  lead-screw  nut  and  move  the  carriage  back  for  the  next  cut  a  distance 
which  must  be  divisble  without  a  remainder  by  the  lead  of  both  the  screw 
being  cut  and  the  lead-screw.  This  position  of  the  carriage  should  be 
noted  by  chalking  the  lathe-bed  or  by  measuring  the  distance  between 
the  thread-tool  and  the  end  of  the  tail-stock  spindle.  Having  carefully 
followed  the  above  instructions  the  lead-screw  nut  may  now  be  reengaged 
and  the  lathe  started,  when  the  tool  will  follow  the  thread  as  accurately 
as  though  the  lathe  had  been  reversed. 

By  marking  the  face-plate,  lead-screw  gear,  and  carriage  positions, 
and  starting  and  stopping  with  these  in  same  positions  for  each  traverse, 
any  thread  will  " catch." 

When  the  number  of  inch-turns  of  the  thread  being  cut  is  a  multiple 
of  the  inch-turns  of  the  threads  on  the  lead-screw,  the  carriage  may  be 
engaged  in  any  position  without  changing  the  alinement  of  thread-tool 
with  thread. 

It  is  not  always  permissible  to  cut  a  groove  for  the  exit  of  the  thread- 
tool,  as  is  done  in  Fig.  413.  Another  way  is  to  drill  a  shallow  hole,  equal 
in  diameter  to  the  width  of  the  thread,  where  the  thread  is  to  stop. 
The  thread-tool  must  be  adjusted  so  as  to  have  the  thread  follow  centrally 
with  the  hole. 


290 


MACHINE-SHOP  TOOLS  AND  METHODS 


Cutting  a  Left-hand  Worm-thread. — A  worm- thread  screw  is  used 
to  operate  a  worm-gear.  Such  gearing  is  commonly  used  in  some  designs 
of  elevators.  It  is  also  used  in  some  lathes  (see  apron  mechanism  in 
chapter  on  Lathes).  The  order  of  operations  for  cutting  the  worm 
shown  in  Fig.  419  may  be  as  follows: 

(1)  Cut  off  machine-steel  stock  19/16"  diameter    by  SVie"    long. 
Center  and  finish  the  ends. 

(2)  Rough  out  blank  all  over,  leaving  it  about  Vie"  larger   than 


T 

§ 

^1 

jt 

T 

One  M.S. 
Tinish  all  over 

FIG.  419. 


FIG.  421. 


in 


T 

i 
f 

\. 

/*• 

---9I-T-- 

A 

DX 

B 

c 
FIG.  420. 

FIG.  422. 


drawing  at  A  and  B,  Fig.  420.     Turn  to  finished  diameter  at  C.    Turn 
shoulders  D  and  E  by  which  to  gage  depth  of  thread. 

(3)  This  thread  being  left-hand,  the  thread  must  be  started  at  the 
left,  and  the  thread-tools  must  (in  effect)  lean  to  the  right.      Rough 
out  thread  with  a  narrow-pointed  round-nose  tool  having  rake,  taking 
care  to  leave  sufficient  stock  for  the  finishing-tool.      Finish  with  tool 
like  that  represented  in  Fig.  421,  testing  thread  by  gage  as  in  Fig.  422. 
Gage  F  may  also  be  used  for  setting  the  tool  in  correct  relation  with 
the  work. 

(4)  Turn  ends  A  and  B  to  size  of  drawing  and  polish  thread  and 
ends  as  in  the  previous  work. 


THREAD-CUTTING  IN  THE  ENGINE-LATHE  291 

Theoretical  Difficulties  in  Thread-cutting.— There  are  certain  theoret- 
ical refinements  connected  with"  thread-cutting  which  are  generally 
neglected  in  ordinary  practice.  ^The  shape  or  angle  of  a  thread  should 
be  measured  in  a  plane'  parallel  with  the  axis  of  the  screw.  But  if  a 
V-thread  tool,  for  instance,  be  ground  to  fit  the  60°  gage  and  adjusted 
to  bring  its  top  face  normal  to  the  sides  of  the  thread  helix  (as  it  should 
be  adjusted  to  make  both  edges  of  the  tool  cut  equally  free)  the  thread 
will  not  be  60°  when  measured  as  indicated  above.  This  may  be  easily 
demonstrated  as  follows:  Place  the  V  point  of  the  thread-gage  between 
the  sides  of  the  thread  with  its  top  face  in  a  plane  passing  through  the 
axis  of  the  screw.  Now  incline  the  gage,  bringing  its  face  to  an  angle 
of  45°  with  the  first  position.  It  will  be  seen  that  the  edges  of  the  gage 
no  longer  fit  the  thread. 

There  are  also  certain  difficulties  in  connection  with  square  and 
other  shapes  of  threads,  but  these  difficulties  are  of  little  importance 
in  threads  of  fine  lead.  In  cutting  threads  of  coarse  leads,  each  side  of 
the  thread  may  be  cut  independently  and  tested  by  a  gage  somewhat 
similar  to  that  shown  in  Fig.  422,  the  latter  being  applied  in  a  plane 
passing  through  the  axis  of  the  screw  as  hi  the  V  thread.  This  method 
has  the  advantage  that  the  tool  may  be  ground  with  side  rake. 

Geometrical  Method  of  Determining  the  Side  Clearance  of  Square- 
thread  Tools. — In  cutting  threads  of  coarse  leads,  special  attention 


FIG.  423 


FIG.  423. 

must  be  given  to  the  side  clearance.  The  following  method,  referring 
to  Fig.  423,  is  taken  from  a  pamphlet  published  by  the  Gisholt  Machine 
Company  descriptive  of  their  universal  tool-grinder: 

"On   the   line  EO  lay  off  OH  equal  to  the  circumference  of  the 
screw  at  the  bottom  of  the  thread,  and  EO  equal  to  the  circumference 


292 


MACHINE-SHOP  TOOLS  AND  METHODS 


at  the  top  of  the  thread.  At  E  and  H  erect  perpendiculars  EF  and 
EL  equal  to  the  pitch  of  the  screw.  Draw  OF  and  OL,  then  will  the 
angle  EOF  be  equal  to  the  angle  of  the  thread  at  the  outside  of  the 
screw,  and  EOL  will  equal  the  angle  at  the  bottom  of  the  thread.  Lay 
off  CAL  and  CEO  equal  to  5°.  Draw  CA  and  CB.  Draw  AB  at  right 
angles  to  the  center  line  CD.  Then  AB  will  be  the  top  of  the  tool  and 
AC  and  BC  the  sides.  By  this  construction  there  will  be  equal  angles 
of  clearance  on  each  side." 

The  top  face  of  the  tool  should  be  normal  to  the  side  of  the  thread 
at  its  mean  diameter,  as  at  AB,  Fig.  424,  and  the  front  edge  should  be 


FIG.  424 


FIG.  424. 

slightly    concave.     These    considerations    are    generally    neglected    on 
threads  4  pitch  and  finer. 

Spacing  Multiple  Threads. — In  cutting  multiple  threads,  the  thread 
may  be  spaced  by  using  the  face-plate  of  the  lathe  as  an  index.  For 
this  purpose  the  slots  in  the  face-plate  should  be  machined  in  the  milling- 
machine  in  connection  with  the  dividing  head.  Thus,  let  it  be  required 
to  cut  a  double  thread.  Now  assuming  that  we  have  two  slots  in  the 
face-plate  diametrically  opposite,  all  that  we  need  to  do  after  cutting 
'the  first  thread  is  to  take  the  work  out  without  unscrewing  the  dog  and 
place  it  back  again  with  the  tail  of  the  dog  in  the  opposite  slot. 


THREAD-CUTTING  IN  THE  ENGINE-LATHE  293 

If  the  lathe  be  geared  one  to  one,  and  the  gear  on  the  stud  have  an 
even  number  of  teeth,  the  double,  thread  may  be  spaced  by  marking  a 
tooth  on  the  stud-gear  to  coincide  with  a  mark  on  the  intermediate 
gear,  and  then  disengaging  the  intermediate  gear  and  turning  the  lathe 
one  half  revolution,  to  bring  the  tooth  diametrically  opposite  in  mesh  at 
the  mark  on  the  intermediate  gear. 


CHAPTER   XIX 


SCREW-THREADS,  TAPS,  AND  DIES— BOLT-  AND  NUT-THREADING 

MACHINES 

U.  S.  Standard  and  V  Thread.— The  subject  of  screw-threads  is  treated 
in  most  books  on  machine  design;  it  is  also  briefly  discussed  in  this 
work  in  connection  with  the  subject  of  screw-cutting.  It  will  be  neces- 
sary however,  to  refer  to  certain  practical  considerations  in  this  con- 
nection. The  simplest  form  of  thread  is  known  as  the  V  thread.  This 
is  generally  so  made  that  the  sides  of  the  V  form  an  angle  of  60°.  The 
objection  to  this  thread  is  that  the  sharp  edges  are  easily  bruised,  and 
also  too  quickly  wear  smaller  than  the  nominal  size; 

Improvements  Affecting  Durability  of  Thread. — To  overcome  both 
of  these  objections  the  thread  known  as  the  U.  S.  standard  has  been 


Da=  P  x  .866 


D  =  H  D:=  P  x  .6495 


V  THREAD 
FIG.  425. 


U.S.  ST'D  THREAD 
FIG.  426. 


FIG.  427. 


introduced.  This  thread  also  has  its  sides  at  an  angle  of  60°,  but  unlike 
the  V  thread  it  is  filled  in  at  the  bottom  of  the  V  and  cut  off  at  the  top, 
forming  flat  tops  and  bottoms.  The  length  of  these  flats  equals  l/%  the 
distance  from  center  of  one  thread  to  the  center  of  the  next.  To  over- 
come the  difficulties  connected  with  the  V  thread,  Sir  Joseph  Whitworth, 
of  England,  originated  the  "  Whitworth  thread."  This  thread  is  rounded 
at  top  and  bottom  and  its  sides  are  55°  included  angle. 

294 


SCREW-THREADS,  TAPS,  AND  DIES 


295 


Difference  in  Effective  Diameters  of  U.  S.  Standard  and  V  Thread.— 

Figs.  425  and  426  show  full-size  views  of  V-thread  and  U.  S.  standard 
screws,  both  being  of  the  same  outside  diameter.  The  center  lines 
passing  through  the  sectioned  ba&s  show  that  there  is  considerable  dif- 
ference in  the  effective  diameters  of  the  two  screws.  This  difference 
may  also  be  seen  in  Fig.  427,  in  which  the  full  lines  show  the  U.  S.  standard 
and  the  dotted  lines,  the  V  thread. 

Square  and  Acme  Thread. — Other  threads  in  common  use  are  the 
square  thread  and  the  acme  thread.  The  square  thread,  as  is  implied 
by  its  name,  has  its  sides  at  right  angles  with  the  axis,  and  is  flat  on  top 
and  bottom.  The  width  of  the  thread  at  top  and  bottom  is  usually  made 
equal  to  its  depth.  As  a  rule  this  thread  is  used  in  places  where  a  long 
screw  and  short  nut  are  required.  In  such  a  case,  if  it  is  desirable  to  have 


2J«23x>.  of  threads  per  in. 


1 


d 

T 


Dia.  of  Tap =0-1- .020 
FIG.  428. 


last  approximately  as  long  as  the  screw,  the  spaces  between  the 
threads  on  the  screw  should  be  wider  than  the  flat  top  of  the  thread. 
This  leaves  the  thread  in  the  nut  thicker  than  in  the  screw. 

For  some  purposes,  as  for  instance  the  lead-screws  on  lathes,  a 
sort  of  compromise  between  the  square  thread  and  the  U.  S.  standard 
is  desirable.  For  these  purposes  a  thread  having  flat  tops  and  bottoms 
and  angling  sides  has  been  used,  but  until  recently  there  has  been  no 
standard  for  this  thread.  A  few  years  ago  Messrs.  Handy  &  Powell 
proposed  a  standard  for  this  thread,  the  proportions  of  which  are  given 


29o  MACHINE-SHOP  TOOLS  AND  METHODS 

in  connection  with  Fig.  428.  These  formulas  are  also  published  in  the 
catalogs  of  the  Brown  &  Sharpe  Manufacturing  Company.  This 
thread  has  its  sides  at  an  angle  of  29°  (included  angle) ,  and  is  known  as 
the  Powell  or  "acme"  thread. 

Pipe-threads. — pipe-threads  are  similar  to  the  60°  V  threads,  except- 
ing that  the  tops  and  bottoms  are  slightly  rounded,  making  the  depth 
only  4/5  of  the  pitch  instead  of  equal  to  the  pitch. 

Considerations  Governing  the  System  of  Threads  to  be  Adopted  in 
Starting  a  New  Plant. — In  starting  a  machine-shop  it  is  necessary  in 
the  outset  to  determine  the  system  of  threads  to  be  used.  The  proper 
thing  to  do  is  to  adopt  the  U.  S.  standard  for  general  purposes,  the  acme 
thread  for  work  of  the  character  of  lathe  lead-screws,  etc.,  and  the  square 
thread  (seldom  used)  as  occasion  may  require.  But  this  is  not  the 
universal  practice.  Some  still  use  the  old  V  thread,  and,  even  when 
supplying  U.  S.  standard,  some  screw-makers — unless  otherwise  ordered 
— will  send  1/2//  screws  with  twelve  threads  per  inch,  when  the  U.  S.  standard 
is  thirteen  for  this  size. 

Variation  from  the  U.  S.  Standard. — For  screws  below  l/±"  very  little 
attention  is  paid  to  the  U.  S.  standard.  The  diameter  of  these  screws 
generally  conforms  to  a  screw-gage  having  decimal  dimensions,  and 
there  is  considerable  variation  respecting  the  pitch.  In  some  special  lines 
of  machinery,  bicycles  for  instance,  there  is  a  very  material  departure 
from  U.  S.  standard.  Some  bicycle-makers  use  twenty  threads  per  inch 
on  the  l/2f  pedal-shaft  where  it  screws  into  the  crank,  and  when  the 
threads  wear  out  in  the  crank,  the  repairer  retaps  it  with  a  5/8"  tap  having 
twenty-four  threads  per  inch,  using  a  bushing  between.  It  is  doubtful 
whether  the  U.  S.  standard  is  adapted  to  work  of  this  character. 

Nominal  and  Actual  Diameter  of  Pipe.  Extra  Strong,  Double 
Extra  Strong,  etc.  —  The  method  of  designating  wrought-iron  pipe 
is  somewhat  confusing  to  the  novice.  When  we  speak  of  a  given  size 
pipe  we  refer  to  the  diameter  of  the  hole.  Thus  1"  pipe  means  pipe 
with  1"  internal  diameter;  but  the  actual  diameter  varies  considerably 
in  some  sizes  from  the  nominal.  1"  pipe  is  1.048"  internal  diameter 
and  2l/<2"  pipe  is  2.468",  the  outside  diameters  being  1.315  and  2.875 
inches  respectively.  Thus  far  there  is  no  special  difficulty,  but  we 
have,  in  addition  to  the  above,  extra-strong  and  double-extra-strong 
pipe.  In  both  the  extra  metal  is  added  to  the  inside,  while  the  pipe 
retains  the  same  designation  as  though  no  change  had  been  made  in  the 
thickness.  Accordingly  1"  extra-strong  pipe  is  .951"  actual  inside 
diameter,  and  1"  double-extra-strong  is  .58"  inside  diameter.  The 


SCREW-THREADS,  TAPS,  AND  DIES 


297 


outside   diameter   remains   1.315"   as   in  the   thin   pipe.     Interchange- 
ability  in  the  fittings  necessitates  t,h£  uniformity  in  the  outside  diameters. 
Taps. — A  tap  is  a  kind  of  steel  j^crew  tempered  and  having  grooves, 
forming  cutting-edges,   cul  lengthwise  the  screw.     There  are  various 


FIG.  429. 

kinds  of  taps  in  use.  Among  the  taps  in  most  common  use  are  hand- 
taps  and  machine-taps,  pulley-taps  and  pipe-taps.  There  are  also 
various  special  taps.  A  standard  set  of  machinists'  hand-taps  is  shown 
in  Fig.  429;  these  are  called  taper,  plug,  and  bottoming  taps  in  the 
order  in  which  they  are  shown  in  the  cut.  The  taper  tap  is  made  taper- 
ing on  the  thread  end  to  facilitate  starting  it  in  the  work.  The  hole  to 
be  tapped  is  drilled  the  same  diameter  as  the  tap  at  the  bottom  of  the 
thread,  or  a  little  larger.  The  tap  is  screwed  into  the  hole  (forming 
thread  as  it  goes)  by  means  of  a  tap-lever  or  wrench  applied  at  the  shank 
end.  If  the  piece  to  be  tapped  is  only  an  inch  or  so  thick  and  the  hole 
passes  quite  through,  the  taper  tap  may  be  screwed  entirely  through  the 
hole  and  the  thread  thus  finished.  If  the  hole  does  not  pass  through 
the  work,  the  plug  tap  may  be  used  to  finish  the  thread  near  the  bottom. 


298  MACHINE-SHOP  TOOLS  AND  METHODS 

It  will  be  noticed  that  the  plug  tap  has  a  short  bevel  on  the  end,  and 
that  the  last  two  or  three  threads  are  imperfect.  If  threads  are  wanted 
at  the  extreme  bottom  of  the  hole  the  bottoming  tap  is  used  to  finish 
the  thread.  All  the  threads  of  this  tap  are  "full." 

Nuts  are  usually  tapped  by  machinery,  a  tap  somewhat  resembling 
the  taper  hand-tap  being  used  for  this  work.  Such  a  tap  is  shown  in 
Fig.  430;  it  is  called  a  machine-tap. 

When  set-screws  are  used  in  the  hub  of  a  pulley  to  secure  it  to  the 
shaft,  the  pulley-tap  is  generally  used.  This  tap  is  shown  in  Fig.  431. 
In  most  cases  the  hole  is  drilled  through  both  the  rim  and  hub,  the  hole 
in  the  rim  being  drilled  slightly  larger  than  the  largest  diameter  of  the 
tap.  The  shank  part  of  the  pulley-tap  is  always  made  quite  long,  so 
that  the  square  end  may  project  through  the  pulley-rim.  Manufacturers 
will  make  pulley-taps  in  lengths  to  suit  the  customer. 

The  Pipe-tap  is  a  short  tap  having  a  taper  on  the  thread  part  of  3/4" 
(in  diameter)  per  foot  of  length.  It  is  used  in  connection  with  steam-  and 
gas-fittings,  etc.  (see  Fig.  432).  The  pipe-tap  is  sometimes  made  with 
the  drill  on  the  end,  so  that  the  hole  may  be  drilled  and  tapped  in  one 
operation.  This  design  is  illustrated  in  Fig.  433,  in  which  D  is  the  drill 
and  S  the  shank.  The  shank  is  made  tapering  to  fit  in  the  spindle  of 
a  ratchet-drill,  by  which  the  tap  is  operated. 

The  tap  used  for  tapping  dies  is  called  a  hob. 

There  is  a  kind  of  bolt  used  to  hold  together  the  inner  and  outer 
plates  on  boiler  fire-boxes.  The  holes  for  these  bolts  are  tapped  with  a 
tool  called  a  stay-bolt  tap.  As  ordinarily  made,  this  is  a  tap  and  reamer 
combined.  It  is  clearly  shown  in  Fig.  434.  The  special  taps  for  other 
purposes  do  not  differ  greatly  from  those  described. 

Thread-dies. — The  moulds  or  forms  used  in  connection  with  presses 
for  making  hollow  ware,  etc.,  are  called  dies.  To  distinguish  the  device 
used  for  forming  threads  on  screws  from  the  latter,  it  should  be  called  a 
thread-die.  Nevertheless  a  thread-die  is  commonly  called  a  die,  and 
we  shall  use  the  same  term  in  this  chapter.  In  cutting  thread  with 
a  die,  the  die  is  screwed  on  the  rod,  cutting  the  thread  as  it  goes. 
Fig.  435  shows  a  "solid"  die,  so  called  because  it  is  not  adjustable.  The 
solid  die  can  be  used  for  one  size  of  screw  only,  and  when  used  to  make 
full  threads  in  one  passage  over  the  screw,  it  soon  wears  larger  than 
standard.  When  used  to  take  a  fine  finishing  cut  only,  being  preceded 
by  a  roughing-die,  it  is  more  reliable. 

Fig.  436  shows  a  sectional  view  and  a  bottom  view  of  a  square  die 
similar  to  that  represented  by  1  ig.  435.  The  openings  A  are  made  to 


SCREW-THREADS,  TAPS,  AND  DIES 


299 


FIG    430. 


FIG.  431.  FIG.  432. 


FIG.  433. 


300 


MACHINE-SHOP  TOOLS  AND  METHODS 


lessen  the  bearing  and  friction,  and  at  the  same  time  they  serve  as  outlets 
for  the  chips.  The  parts  E  are  referred  to  as  the  lands.  The  advancing 
edge  of  the  land  is  the  cutting-edge  and  the  remaining  part,  the  heel. 


REAMER 


THREAD 
TAPER  j  STRAIGHT! 


SHANK 


FIG.  434. 


Making  a  Solid  Die. — The  general  principles  employed  in  making 
a  square  solid  die  are  very  much  the  same  as  for  other  dies,  and  it  may 
be  well  to  describe  a  method  of  making  this  die.  In  factories  where 


FIG.  435. 


FIG.  436. 


taps  and  dies  are  made  as  a  specialty  the  best  facilities  must,  of  course, 
be  employed;  but  the  method  that  we  shall  describe  is  a  kind  of  " home- 
made "  plan,  applying  to  the  making  of  a  single  die.  The  short  diameter 
of  the  square  die  may  be  2x/4  times  the  diameter  of  the  bolt  to  be  cut, 
and  its  thickness  may  be  about  I1/ 4  times  the  diameter  of  the  bolt.  When 
a  number  of  different  sizes  of  dies  are  to  fit  one  stock,  the  dimensions 
of  some  of  them  would  be  greater  than  above  indicated. 

Having  forged  and  machined  the  die  blank  to  the  proper  dimensions, 
the  next  thing  in  order  is  to  drill  it.  The  center  of  the  blank  may  be 
established  by  drawing  intersecting  lines  diagonally  across  its  face,  and 
after  prick-punching  the  center,  two  circles,  one  the  diameter  of  the 
drill  and  the  other  somewhat  larger,  should  be  drawn  on  the  blank. 
The  surface  of  the  blank  may  be  covered  with  blue  vitriol  to  take  clearly 


SCREW-THREADS,  TAPS,  AND  DIES  301 

defined  lines.  The  drilling  is  usually  done  in  the  lathe,  the  blank  being 
held  in  the  chuck  or  strapped  to  the  face-plate.  The  blank  may  be 
adjusted  by  the  circles  in  connection  with  a  scriber  held  in  the  tool- 
post.  The  tang  of  an  old  file  ground  to  a  point  is  sometimes  used  for 
this  purpose.  Again,  some  prefer  to  use  an  indicator.  The  hole  for 
the  thread  in  the  solid  die  should  be  made  equal  to  the  bottom  of  the 
thread  of  the  bolt  to  be  cut.  It  may  be  drilled  and  bored  according  to 
instructions  given  elsewhere  for  such  operations. 

Having  made  the  hole  of  the  required  size,  the  thread  must  next  be 
cut.  The  threading  may  be  done  by  an  inside  thread-tool,  using  good 
lard-oil  as  a  lubricant.  The  finishing  cuts  should  be  very  light,  and  the 
thread-tool  for  this  purpose  should  be  in  the  best  possible  condition.  If 
a  good  tap  of  the  right  size  be  available,  it  would  be  well  to  take  the 
finishing  cut  with  this  tap;  but  as  the  pitch  of  taps  is  sometimes  slightly 
altered  in  the  hardening  process,  the  thread  must  not  be  cut  too  near 
the  final  size  with  the  thread- tool,  lest  the  tool-marks  be  seen  after  the 
hole  has  been  tapped. 

Before  taking  the  die  out  of  the  chuck,  the  hole  should  be  chamfered 
back  a  distance  equal  to  about  one  third  the  thickness  of  the  die,  as 
shown  at  C  in  Fig.  436.  The  largest  diameter  of  the  chamfer  should 
be  slightly  greater  than  the  diameter  of  the  bolt.  It  will  be  understood 
that  the  object  cf  chamfering  the  die  is  to  facilitate  starting  the  thread 
on  the  bolt. 

After  cutting  the  thread  the  next  operation  is  to  drill  the  clearance 
holes  lettered  A.  These  should  not  be  less  than  half  the  diameter  of 
the  bolt.  The  centers  for  these  holes  may  be  located  on  the  diagonal 
lines  previously  made,  at  the  intersection  of  a  circle  I1/ 4  times  the  diam- 
eter of  the  bolt.  This  circle  will,  of  course,  be  drawn  from  the  center 
of  the  threaded  hole. 

To  prevent  the  drill  from  "running"  toward  the  threaded  hole,  it  is 
customary  among  some  mechanics  to  plug  the  hole  with  a  screw  tightly 
fitting  the  thread  and  filed  flush  with  the  surface  of  the  die.  Others 
prefer  to  dispense  with  the  plug  and  drill  small  holes  first,  enlarging 
same  with  counterbore.  These  clearance  holes  may  be  drilled  in  the 
drill-press. 

When  this  work  is  done,  the  die  is  ready  to  be  filed.  For  general 
work,  including  brass,  the  front  of  the  cutting-edge  may  be  filed  radial, 
though  some  prefer  to  give  the  cutting-edges  rake,  for  wrought  iron. 
For  a  die  having  four  cutting-edges,  the  width  or  thickness  of  the  lands 
may  be  about  3/ie  to  x/4  the  diameter  of  the  bolt.  The  chamfered  part 


302  MACHINE-SHOP  TOOLS  AND  METHODS 

•of  the  die  must  also  be  filed  to  give  the  heel  clearance.  Great  care  is 
required  in  this  work  to  keep  the  file  from  cutting  the  extreme  points 
of  the  teeth  at  the  advancing  edge.  The  filing  should  be  begun  at  the 
heel  and  barely  brought  up  to  the  edge  without  touching  it.  Some  file 
or  "back  off"  the  heel  beyond  the  chamfered  part — that  is  through  the 
full  length  or  thickness  of  the  die. 

The  size  of  the  die  should  be  stamped  on  its  face  before  the  die  is 
hardened.  , 

Adjustable  Dies. — Adjustable  dies  are  made  in  a  great  variety  of 
forms,  and  the  die-stocks  differ  as  much  as  the  dies.  Fig.  437  shows 
one  design,  in  which  S  is  the  die-stock  and  DD  the  die  in  two  parts; 
the  adjustment  is  by  means  of  the  screw  A.  Grooves  are  cut  on  the 
edges  of  the  die,  as  shown  in  Fig.  438,  to  fit  over  the  guides  G.  The 
latter  are  pivoted  in  the  stock  and  are  swung  outward  to  remove  the 
die.  Dies  of  this  construction  are  usually  drilled  and  tapped  larger  than 
the  diameter  of  the  bolt  they  are  to  cut.  Sometimes  the  drill  used  is 
equal  to  the  outside  diameter  of  the  bolt,  the  tap  or  hob  being  the  diam- 
eter of  the  bolt  plus  twice  the  depth  of  the  thread.  This  gives  the 
thread  a  full  bearing  on  the  bolt  when  first  started  and  prevents  a 
"drunken"  or  irregular  thread.  In  using  these  dies  several  cuts  are 
sometimes  taken  to  make  a  full  thread,  and  by  tapping  the  die  out 
large  as  above  indicated,  the  bearing  in  the  thread  and  the  relative 
degree  of  friction  are  decreased  at  the  time  when  the  hardest  work  is 
being  done,  viz.,  when  the  thread  is  approaching  full  depth.  The  adjust- 
ment of  the  die  is  sufficient  to  allow  the  two  parts  of  the  die  to  be  separated 
enough  to  be  quickly  withdrawn  from  the  bolt  without  reversing  the 
die  when  the  end  of  the  thread  is  reached. 

Pratt  &  Whitney  Adjustable  Die. — In  the  die  illustrated  in  Fig.  439, 
four  detachable  "chasers"  are  used,  the  limit  of  adjustment  being 
1/32//-  The  chasers  are  held  in  a  head  somewhat  similar  to  that  shown 
in  Fig.  440.  The  latter,  however,  is  designed  more  particularly  for 
brasswork.  The  head  represented  by  Fig.  439  may  be  held  in  a  stock 
like  that  shown  in  Fig.  441.  It  may  also  be  held  in  a  turret-head. 

The  Solid  Pipe-die  differs  so  little  in  general  construction  from 
the  solid  bolt-die  as  to  need  no  description.  Pipe-dies  are  made  also 
in  adjustable  form. 

Retapping  Old  Dies.— Mr.  Geo.  J.  Meyer  in  "American  Machinist," 
vol.  26,  page  1293,  suggests  that  the  retapping  of  old  dies  may  be 
facilitated  by  filling  the  clearance  holes  with  babbitt.  To  prevent 
the  babbitt  from  running  into  the  thread,  he  plugs  the  hole.  After  the 


SCREW-THREADS,  TAPS,  AND  DIES 


303 


die  has  been  retapped  the  babbitt  is,  of   course,  driven  out,  a  punch 
being  used  for  this  purpose.     Mr.  Meyer  recommends  filling  up  the  flutes 


FIG.  438. 


FIG.  437. 


FIG.  439. 


of  taps  also  when  these  are  to  be  recut.     The  flutes  are  tinned  to  make 
the  babbitt  adhere. 

Making  the  Taper  Tap  of  the  Set  of  Hand-taps.— The  steel  used  for 
making  taps  should  be  of  high  grade — such  as  is  recommended  by  steel 
manufacturers  for  this  purpose.  In  order  to  insure  the  removal  of  the 
decarbonized  surface  of  the  metal,  stock  should  be  selected  of  a  diameter 
not  less  than  3/32"  larger  than  the  diameter  of  the  tap.  In  this  con- 
nection read  in  Chapter  X  the  paragraph  on  Hardening  Reamers.  For 


304  MACHINE-SHOP  TOOLS  AND  METHODS 

softening  the  steel  some  mechanics  prefer  the  "water  anneal."    This 
process  consists  in  heating  the  steel  to  a  low  red,  holding  it  in  a  dark 


•J 


FIG    440 


place  until  the  color  leaves  the  steel,  and  then  plunging  it  into  soap?/  water. 
Oil  is  used  by  some  mechanics  for  the  bath.  The  "water  anneal"  is 
preferred  to  the  softer  annealing,  because  when  too  soft  the  thread  seems 


c 

FIG.  441. 


inclined  to  tear,  and  it  is  difficult  to  make  the  tool  cut  smoothly.  Other 
mechanics,  however,  adhere  to  the  slower  method  of  annealing. 
Mr.  E.  R.  Markham,  whose  articles  on  tool-making  in  machinery  have 
been  consulted  by  the  author  in  connection  with  this  work,  heats  the 
tap-blank  to  a  low  red,  places  it  between  two  pieces  of  board  and  buries 
it  in  a  box  of  ashes.  Mr.  Markham  says  respecting  this  method:  "The 
steel  cooled  below  a  red  very  quickly,  but  the  boards,  which  were  charred 
from  contact  with  the  red-hot  steel,  kept  the  piece  of  steel  hot  for  a  long 
time."  He  says  further,  referring  to  the  tap-blank,  "It  should  not 
remain  red-hot  any  longer  than  is  necessary  to  insure  its  not  being 
chilled,  yet  it  should  cool  very  slowly  from  a  point  just  below  red  heat. 
Much  of  the  steel  that  is  annealed  is  subjected  to  heats  that  are  too  high. 


SCREW-THREADS,  TAPS,  AND  DIES 


305 


This  opens  the  grain  and  weakens  the  steel,  and  it  crumbles  off  and 
tears  when  cut  with  a  threading-rtool." 

Having  annealed  the  tap-blank,,  which  we  shall  assume  to  be  of  a  diam- 
eter suitable  for  a  3/4"  frap,  and  of  a  length  six  times  the  tap  diameter 
plus  about  Vie",  the  blank  should  now  be  centered  and  its  ends  faced 
to  41/2//  long.  Next  rough  out  the  blank  all  over  and  turn  the  shank  end 
as  shown  in  Fig.  442.  Now  mill  the  ends  square  for  the  tap-wrench  and 


„ 

L  a,//     J 

**2—  - 

H 

*  H      -») 

*-     "ft 

ct 

i 

*  i 

v  i 
g 

!B 
i 

C 

L-  —  — 

i 

J 

I* 

1 
4- 

FIG.  442 

stamp  the  size  of  the  tap  on  the  round  part  of  the  shank.  With  a  dog  on 
square  end  of  the  tap,  using  brass  to  avoid  marring  the  end,  the  part 
that  is  to  be  threaded  may  next  be  turned  to  size.*  This  is  sometimes 
turned  at  D  .001  to  .003  inch  larger  than  the  nominal  diameter,  to 
compensate  for  the  wear  on  top  of  the  teeth. 

Threading  the  Tap. — The  next  operation  is  to  cut  the  thread.  It 
may  be  cut  parallel  f  at  the  root  and  of  the  same  diameter  as  B  in  the 
sketch,  this  being  the  diameter  of  a  3/4"  U.  S.  standard  screw  at  the 
root  of  the  thread.  It  should  be  unnecessary  to  give  in  this  connection 
detailed  instruction  for  grinding,  setting  the  thread-tool,  etc.  What 
has  been  said  in  the  chapter  on  thread-cutting  will  apply  equally  well 
here.  Tap-making,  however,  is  a  higher  grade  of  work  than  ordinary 
thread-cutting,  and  special  care  will  be  required  for  this  work.  Good 
lard-oil  should  be  used,  and  the  finishing  cuts  should  be  very  light.  The 
tap  should  be  gaged  by  some  instrument  the  measuring-points  of  which 
bear  on  the  angular  sides  of  the  thread.  Either  the  screw-thread 
micrometer,  Fig.  20,  or  the  thread-gage  shown  in  Fig.  30  will  answer. 

Small  taps  are  sometimes  cut  with  dies.  Several  dies  are  used  for 
each  size,  the  finishing-die  taking  a  very  light  cut.  On  the  same  principle 
dies  are  also  threaded  with  several  taps  or  hobs.  In  either  case  if  the 

*  Instead  of  turning  the  tapering  part  of  the  tap  (part  between  E  and  (?) 
before  the  thread  is  cut,  many  tool-makers  cut  the  thread  first. 

t  The  practice  of  some  manufacturers  is  to  make  the  three  hand-taps  parallel 
and  of  the  same  diameter  at  the  root  of  the  thread.  Others  taper  the  root  of  the 
thread  from  E  to  C,  making  it  smaller  at  E  than  the  root  diameter  of  the  screw. 


306 


MACHINE-SHOP  TOOLS  AND  METHODS 


CUTTER 


FlG.   443. 


FORM  OF  TAP 
FlG.   444. 


lathe  gearing  be  dispensed  with  altogether,  the  lead  of  tap  or  die  is  likely 
to  be  slightly  too  long.  Nevertheless  the  results  are  satisfactory  for 
most  purposes. 

Grooving  the  Tap. — For  this  purpose  a  cutter  like  that  represented 
by  Fig.  443,  making  four  grooves  as  shown  in  Fig.  444,  may  be  used. 

The  lands  may  be  of  the  same 
width  as  in  the  die,  viz.,  3/16  to 
J/4  the  tap  diameter,  the  cutter 
being  fed  a  depth  which  will  leave 
this  width.  Cutters  for  the  above 
purpose  are  carried  in  machinery 
supply  stores. 

Taps  are  generally  grooved  in 
the  miller,  but  if  such  a  machine 
is  not  available  a  simple  fixture 

may  be  improvised  and  used  on  the  lathe-rest  in  connection  with  a 
revolving  cutter,  the  latter  being  driven  by  an  arbor.  The  fixture  may 
be  constructed  as  follows:  make  a  casting  with  two  standards  or  lugs,* 
and  a  center  in  each  lug.  One  of  these  lugs  could  be  made  adjustable 
longitudinally  in  a  slot,  and  the  center  in  this  lug  could  be  threaded 
for  lengthwise  adjustment.  The  other  center  should  be  so  arranged  as 
to  admit  of  being  rotated,  and  should  carry  a  small  face-plate  having  a 
slot  for  the  tail  of  the  dog.  Four  or  more  notches  equally  spaced  around 
the  periphery  of  the  plate  and  a  spring  pawl  to  engage  these  notches 
complete  this  pair  of  centers. 

Backing  Off  the  Tap. — The  tapered  part  of  the  tap-lands  must  be 
backed  off  or  filed  for  the  same  reason  that  the  chamfered  part  of  the 
die  was  filed,  and  with  the  same  precaution  respecting  the  cutting-edges. 
The  amount  of  this  clearance  must  be  determined  by  observation  and 
good  judgment.  To  remove  any  roughness  left  by  the  cutter,  the  face 
of  the  cutting-edge  and  back  face  of  the  land  should  be  smoothed  with 
emery-wheel  or  file. 

Relieving  the  Tap. — Taps,  especially  taper  taps,  cut  much  more 
easily  when  relieved  or  given  clearance  between  the  teeth.  A  three- 
cornered  or  half-round  file  may  be  used  for  this  work.  Here  again 
care  must  be  exercised  to  protect  the  cutting-edges.  Some  workmen 
object  to  this  clearance  on  the  ground  that  it  causes  chips  to  wedge 
between  the  teeth  when  the  tap  is  reversed. 

*  If  the  fixture  be  bolted  on  top  of  the  rest,  one  end  of  the  casting  may  need 
a  downward  offset  for  clearance  of  dog. 


SCREW-THREADS,  TAPS,  AND  DIES 


307. 


Relieving  Taps  by  Etching-fluid. — Taps  of  abrupt  taper  do  not  cut 
freely,  because  the  threads  are  greater  in  diameter  at  the  heel  of  the  land 
than  at  the  cutting-edge.  The 'threads  may  be  relieved  by  etching-fluid 
in  the  same  manner  that  steel  t$bls  are  marked. 

Tempering  Taps  and  Dies. — The  paragraph  on  hardening  reamers 
referred  to  above  will  apply  to  taps  and  dies.  Additional  care,  how- 
ever, may  be  necessary  to  protect  the  points  of  the 
tap-teeth.  The  cutting  parts  of  both  tap  and  die  may 
be  drawn  to  a  straw  color,  but  the  die  will  be  stronger 
if  the  outside  edges  are  somewhat  softer.  To  insure 
free  circulation  of  water  between  the  cutting-edges, 
move  the  die  back  and  forth  in  the  bath. 

After  hardening  the  tap,  it  may  be  polished  on  a 
buffing-wheel  or  with  emery-cloth.  The  inexperienced 
workman  is  cautioned  against  rounding  the  points  of 
the  teeth  and  spoiling  the  tap  in  this  operation.  It  is 
scarcely  necessary  to  polish  the  die. 

The  plug  and  bottoming  taps  need  differ  from  the 
taper  tap  only  in  the  turning,  the  threading  being  the 
same.  However,  to  avoid  tapping  a  hole  slightly  larger 
at  the  entrance  end,  plug  and  bottoming  taps  are 


w 


FIG.  445. 


FIG    446. 


sometimes  made  to  taper  smaller  towards  the  shank.  When  this  expe- 
dient is  used,  the  amount  of  the  taper  should  be  so  little  as  to  be  scarcely 
appreciable.  A  fraction  of  a  thousandth  of  an  inch  smaller  will  be  quite 
sufficient. 


308 


MACHINE-SHOP  TOOLS  AND  METHODS 


Tapping  Holes.  The  Tap-lever. — In  tapping  holes  beginners  will 
depend  on  the  hole  to  guide  the  tap,  but  this  is  generally  disappointing, 
as  the  tap  will  not  always  follow  square.  The  proper  way  is  to  apply 
a  square  to  the  tap  as  soon  as  it  takes  hold ;  if  the  tap  incline  to  the  left 
apply  pressure  on  the  right  side.  It  is  generally  necessary  to  test  the  tap 
several  times  before  it  is  properly  started.  Fig.  445  shows  a  method 
of  starting  a  tap  and  applying  the  •  square.  Great  care  is  required  in 
using  small  taps,  as  they  are  apt  to  snap  off,  especially  when  applying 
greater  pressure  on  one  side  to  square  the  tap. 

In  tapping  steel,  wrought  iron,  etc.,  it  is  usually  necessary  for  every 
one  half  to  three  fourths  revolution,  to  rotate  the  tap  backward  a  fraction 
of  a  revolution  in  order  to  dislodge  the  chips.  This  is  sometimes  advan- 
tageous also  in  tapping  cast  iron.  Tool  steel  can  best  be  tapped  with 
a  mixture  of  lard-oil  and  graphite. 

The  tap-lever  may  be  of  some  adjustable  form,  as  that  shown  in  Fig. 
446,  for  instance ;  or  a  simple  lever  with  a  square  hole  in  the  center  may 
be  used.  Adjustable  levers  for  taps  and  reamers  are  made  in  many  designs. 
The  one  shown  is  so  simple  that  no  explanation  will  be  necessary. 

Threading  Large  Work. — It  is  sometimes  necessary  to  thread  some 
special  casting  in  which  the  hole  is  too  large  for  any  tap  on  hand,  while 


the  casting  is  too  large  to  be  threaded  in  any  available  lathe.  Fig.  447 
illustrates  a  case  of  this  kind.  The  work  is  bolted  to  a  planer-bed  and 
a  special  boring  bar  B,  supported  in  a  guide  bracket  G,  is  used — first  to 


BOLT-CUTTING  AND  NUT-f  APPING  MACHINES 


309 


finish  the  hole,  and  next  to  cut  the  thread  as  shown.  The  bushing  B  I 
may  be  made  with  fine  thread  for  feeding  the  bar  when  boring  out  the 
hole,  and  one  with  the  required  thread  must  be  made  for  threading  the 
hole.  Bushing  B  2  requires  no  thread.  Having  adjusted  the  guide 
bracket  and  cutters  in  the  bar  to  the  work,  the  bar  is  turned  by  a  wrench 
on  the  square  end  P.  If  much  of  this  work  is  required  the  bar  could 
be  operated  by  power.  When  the  bar  is  turned  the  thread  on  B  forces 
the  bar  to  advance  a  distance  equal  to  the  lead  of  its  thread  for  each 
revolution.  Several  cuts  are  .required  to  complete  the  thread. 
Tables  of  tap-drill  sizes  are  given  on  pages  516  to  518. 


BOLT-CUTTING   AND    NUT-TAPPING   MACHINES 

Bolt-cutter. — The  machine  shown  in  Fig.  448  is  one  of  the  smallest 
and  simplest  bolt-cutters  supplied  by  the  makers.     The  bolt  is  held 


LI 


in  the  vise  V,  being  clamped  by  the  lever  L.    The  carriage  carrying 
the  vise  is  fed  to  the  die  D  by  the  lever  LI.     By  the  contact  of  the 


310 


MACHINE-SHOP  TOOLS  AND  METHODS 


ADJUSTING 
SCREW 


FIG.  450. 


BOLT-CUTTING  AND   NUT-TAPPING  MACHINES  311 


FIG.  453. 


312  MACHINE-SHOP  TOOLS  AND  METHODS 

bracket  B  with  the  adjustable  stop  S  the  die  is  automatically  opened  to 
release  the  bolt  when  the  thread  is  cut  the  required  length.  The  car- 
riage is  then  quickly  withdrawn  while  the  die-head  continues  to  run 
in  the  forward  direction.  The  multiple-spindle  machines  are  more 
elaborate  and  turn  out  a  great  quantity  of  work. 

Die-head. — One  of  the  most  important  features  of  these  machines 
is  the  die-head.  The  front  view  of  this  head  is  illustrated  in  Fig.  449, 
the  sectional  view  being  shown  in  Fig.  450.  Fig.  451  shows  a  perspective 


view.  The  names  of  the  various  parts  are  given  in  connection  with  the 
first  two  illustrations.  As  will  be  seen,  the  die-chasers  are  guided  in 
radial  slots  at  the  front  end  of  the  head.  The  movement  of  the  chasers 


BOLT-CUTTING  AND  NUT-TAPPING  MACHINES  313 

in  and  out  is  controlled  by  the  die-ring.  The  latter  is  in  turn  operated 
by  the  clutch-ring,  to  which  it  ( is  connected  by  a  rocking  lever  and 
toggle.  Most  or  all  of  the  sliding  surfaces  are  tool  steel  or  have  tool-steel 
linings. 

One  of  the  chasers  is  shown  in  detail  in  Figs.  452  and  453,  the  latter 
figure  showing  also  a  reamer  to  indicate  how  the  dies  are  chamfered. 

Six-spindle  Nut-tapper  (Fig.  454). — In  this  machine,  the  taps  are 
connected  to  the  lower  end  of  the  spindles,  the  nuts  being  held  under 
the  taps  in  adjustable  holders.  Each  spindle  is  lifted  by  either  a  lever 
or  a  treadle  as  indicated.  "The  spindles  are  counterbalanced  to  pre- 
vent breaking  the  taps,"  and  each  spindle  may  be  stopped  inde- 
pendently of  the  others.  The  taps  can  be  removed  while  the  machine 
is  in  operation.  The  lubricant  is  automatically  pumped  to  the  tap. 


CHAPTER  XX 
THE  BORING-BAR  AND  ITS  USE 

Definition  and  Classification  of  Boring-bars. — A  boring-bar  is  a  bar 
of  metal  bearing  one  or  more  cutters  for  enlarging  and  correcting  holes. 
Boring-bars  may  be  classified  as  follows:  first,  the  plain  bar  with  cutter 
directly  secured  to  same  (Fig.  455);  second,  the  bar  having  a  fixed 


FIG.  455. 


cutter-head  with  cutters  secured  to  the  head  (Fig.  456) ;  third,  the  sliding- 
head  bar,  the  head  of  which  is  adapted  to  be  fed  along  by  a  screw  and 


FIG.  456. 

star-shaped  wheel,  as  in  Fig.  457.    This  feeding  device  is  called  the  star 
feed. 

Securing  the  Cutters  in  the  Bars. — There  are  various  methods  for 
securing  the  cutters  in  the  bars.     The  cutter  represented  by  Fig.  455  is  of 

314 


THE  BORING-BAR  AND  ITS  USE 


315 


rectangular  cross-section,  and  is  held  in  a  rectangular  slot  in  the  bar  by 
means  of  a  set-screw;  the  rectangular  slot  shown  in  Fig.  458  is  made 


r  to  keep  head  A 
^f      from  turning 


PIG.  457. 

longer  than  the  width  of  the  cutter  in  order  to  receive  a  key  which 
secures  the  cutter  to  the  bar;  the  cutter  illustrated  in  Fig.  459  is  held 
by  a  threaded  collar  which  screws  on  the  bar. 


Boring  a  Steam-engine  Cylinder.— As  indicated  in  the  definition,  a 
boring-bar  is  never  used  to  originate  a  hole,  but  always  to  enlarge  a  hole. 
As  will  be  presently  shown,  the  boring-bar  is  used  in  various  ways.  A 
clear  conception  of  the  boring-bar  may  be  had  by  the  consideration  of  one 
of  its  most  common  uses,  viz.,  that  of  boring  steam-engine  cylinders.  In 
boring  a  single  cylinder  in  the  lathe,  the  cylinder  is  generally  secured  to 
the  lathe-carriage  by  common  machine-shop  bolts  and  straps,  the  cylinder 
being  raised  to  the  correct  height  by  blocks,  wedges,  etc.  If  a  large 
number  of  cylinders  are  to  be  bored  a  special  fixture  is  made  to  support 
the  cylinders  on  the  lathe-carriage.  To  adjust  the  cylinder  in  alinement 
with  the  lathe-spindle  a  testing-rod  is  commonly  used  in  connection 
with  the  boring-bar,  though  some  mechanics  prefer  to  aline  the  cylinder 
by  calipering  from  the  cylinder-flange  to  the  bar.  Fig.  460  shows  a 


316 


MACHINE-SHOP  TOOLS  AND  METHODS 


cylinder  bolted  to  a  lathe-carriage  and  illustrates  the  method  of  using 
the  testing-rod.     The  latter,  which  is  shown  at  R,  may  be  made  of 


Adjusting  Nut 


Washer 


FIG.  459. 


1/4//  round  or  square  steel  and  held  in  the  slot  of  the  bar  by  a  wooden 
wedge. 

To  test  the  alinement  of  the  cylinder,  the  boring-bar  is  slowly  revolved 
on  the  lathe-centers  by  hand  (or  the  lathe,  driving  the  bar  by  a  dog  or 


n 


METHOD  OF  ADJUSTING  A  CYLINDER 
FIG.  460. 

rod,  is  slowly  revolved)  and  the  position  of  the  cylinder  in  relation  to 
the  revolving  rod  noted.  If  the  point  of  the  testing-rod  does  not  clear 
the  cylinder  by  the  same  amount  at  three  of  four  points  around  the 
cylinder-flange,  the  bolts  are  slackened  and  the  cylinder  is  moved  in  the 
direction  indicated  by  the  revolving  rod,  this  process  being  continued 
for  each  end  of  the  cylinder  until  it  is  found  to  be  in  alinement  with 
the  bar.  If  now  the  tail-stock  of  the  lathe  be  axially  true  with  the 


THE  BORING-BAR  AND  ITS  USE  317 

lathe-spindle,  the  cylinder  will  also  be  in  alinement  with  the  lathe-spindle 
as  required. 

When  the  adjusting  and  clamping  is  completed  the  cylinder  may  be 
bored  by  feeding  the  carriage  bearing  the  cylinder  toward  the  revolving 
cutters;  or,  if  a  sliding-head  bar  be  used,  the  carriage  is  held  stationary 
and  the  head  while  revolving  is  fed  through  the  cylinder.  It  will  require- 
at  least  two  cuts.  The  first  cut  rough-bores  the  cylinder;  the  second 
cut,  which  requires  cutters  having  broader  edges,  smooths  the  bore 
and  brings  it  to  the  final  diameter. 

A  method  of  "truing-up"  cylinders  by  the  end  flanges  has  been 
referred  to;  if  a  cylinder  has  not  these  flanges,  the  method  of  adjust- 
ment must  be  determined  to  suit  the  design  of  the  cylinder.  Further 
instructions  respecting  fixtures  for  holding  and  adjusting  cylinders  are 
given  in  connection  with  Figs.  480  and  481.  When  one  of  these  special 
fixtures  is  used  very  little  adjusting  is  necessary. 

Single  and  Double  Cutters  Compared. — The  number  of  cutters  in 
a  boring-bar  varies  with  the  size  of  the  bar.  There  may  be  one  or  a 
dozen,  or  even  two  dozen  for  very  large  bores.  When  a  single  cutter 
is  used  it  may  be  made  with  one  or  two  cutting-edges.  If  made 
with  one  cutting-edge  it  cuts  on  only  one  side  of  the  bar.  In  this 
case  the  cutter  is  unsupported  on  the  opposite  side  of  the  bar,  except 
in  so  far  as  it  is  supported  by  the  bar  itself.  In  very  small  holes  the 
bar  is  quite  frail  and  does  not  adequately  support  the  pressure  of  the 
cut;  the  single  cutter  is,  therefore,  not  well  adapted  to  long  holes  of 
small  diameter.  In  using  the  cutter  which  has  cutting-edges  on  both 
ends,  the  cut  on  one  side  of  the  bar  is  supported  by  a  corresponding  cut 
on  the  opposite  side,  and  thus  the  bar  is  under  a  torsional  stress  only. 
If  a  cutter  with  one  cutting-edge  be  used,  the  bar  will  be  subjected  to 
both  torsion  and  flexure. 

A  single  cutter  has  the  advantage  that  it  may  be  adjusted  for  dif- 
ferent sizes  of  holes,  while  the  double  cutter,  as  originally  made,  may 
be  used  for  one  size  only.  However,  the  double  cutter  may  be  made 
in  two  parts,  as  illustrated  in  Fig.  461.  With  this  construction  we 
have  the  advantages  of  both  the  single  and  double  cutter,  excepting 
that  the  double  cutter  is  not  self-adjusting,  as  it  is  represented  in  Fig. 
458.  The  above  refers  to  the  plain  bar. 

Fixed-head  Bar. — The  second  boring-bar  mentioned  in  the  classifica- 
tion is  in  principle  similar  to  the  first ;  that  is  to  say,  the  cutters  are  held 
in  a  fixed  position  respecting  the  bar.  The  head  is  used  on  the  bar 
merely  to  provide  for  boring  large  holes  without  enlarging  the  bar 


318 


MACHINE-SHOP  TOOLS  AND  METHODS 


throughout  its  length.  The  head  may  be  secured  to  the  bar  by  means 
of  a  common  key  as  shown  in  Fig.  456,  in  which  H  is  the  head,  B  the  bar, 
K  the  key,  and  C  the  cutters,  or  the  head  may  be  held  by  set-screws. 


Spindle  of 

Drilling  Machine 


FlG.  461. 

This  figure  shows  also  one  method  of  holding  the  cutters,  but  some 
prefer  to  hold  them  by  set-screws. 

The  design  shown  in  Fig.  462,  in  which  round  cutters  are  used,  sug- 
gests itself  in  this  connection.  The  illustration  is  a  sectional  view  of 
a  cutter-head  held  on  the  bar  by  two  set-screws.  Two  methods  of 
holding  and  adjusting  the  cutters  by  set-screws  are  shown.  The  cutter 
at  C  1  is  adjusted  by  a  small  rod  in  connection  with  the  screw  S,  which 
engages  directly  with  the  end  of  the  cutter.  The  cutter  C  2  is  forced 
out  by  contact  of  the  conical  point  of  the  screw  S  I  with  the  beveled 
end  of  the  cutter.  It  will,  of  course,  be  understood  that  the  two  methods 
of  adjusting  the  cutters  are  not  to  be  used  in  the  same  head. 

A  cutter-head  might  be  made  of  such  a  design  that  all  the  cutters 
could  be  forced  out  simultaneously.  Thus  the  beveled  edges  of  the 
cutters  could  be  seated  on  the  beveled  edge  of  a  ring,  the  ring  being 
forced  against  the  cutters  by  a  nut  screwed  on  the  bar. 

The  holes  or  slots  for  the  cutters  should  in  nearly  all  cases  be  made 


THE  BORING-BAR  AND  ITS  USE 


319 


to  fit  bar  stock,  or  so  nearly  to  bar-stock  size  that  a  few  touches  of 
the  file  will  reduce  the  rough  stock  to  the  size  of  the  holes. 

When  round  cutters  are  used*  a  flat  seat  should  be  filed  on  the  side 
of  each  cutter  to  receive  the  sefciecrew  which  binds  it.    Cutters  should 


-ct 


TWO  METHODS  OF  ADJUSTING  CUTTERS 
FIG.  462. 

be  of  square  or  rectangular  cross-section,  however,  when  they  are  ad- 
justed by  a  wedge. 

The  enlarged  collar,  which  we  have  called  the  cutter-head,  is  some- 
times made  integral  with  the  bar;  but  this  arrangement  is  disadvan- 
tageous when  we  wish  to  use  one  bar  for  different  sizes  of  heads. 

The  Sliding-head  Bar. — The  third  bar  mentioned  in  the  classifica- 
tion is  a  radical  departure  from  the  other  two  designs.  It  is  shown  in 
Fig.  457.  We  have  called  this  the  sliding-head  bar  because,  instead 
of  being  fixed  to  the  bar,  the  head  slides  lengthwise  the  bar  by  automatic 
mechanism.  This  mechanism  consists  of  the  long  screw  lengthwise  the 
bar  which  engages  with  a  threaded  hole  in  the  head.  On  the  tail-stock 
end  of  the  bar  is  a  small  lug  which  serves  as  the  bearing  for  the  screw 
and  also  sustains  the  end  thrust  of  the  screw.  At  the  same  end  of  the 
bar  and  on  the  extreme  end  of  the  screw  is  a  small  star-shaped  device 
(marked  Star)  the  points  of  which,  when  the  bar  revolves,  engage 
with  a  fixed  projection  on  the  tail-stock.  The  effect  of  this  arrangement 
is  to  cause  an  intermittently  revolving  movement  of  the  screw,  which 
in  turn  causes  a  lengthwise  movement  of  the  head.  The  head  is  pre- 
vented from  revolving  on  the  bar  by  means  of  a  feather-key  the  full 
length  of  the  bar,  which  key  engages  with  a  corresponding  keyway  in  the 


320  MACHINE-SHOP  TOOLS  AND  METHODS 

head.  The  head,  of  course,  has  the  motion  due  to  the  revolutions  of 
the  bar,  excepting  some  special  cases  in  which  the  work  instead  of  the 
bar  revolves. 

It  is  not  essential  to  the  successful  operation  of  the  bar  that  the  star 
device  be  placed  on  the  tail-stock  end  of  the  machine,  nor  is  the  shape  or 
position  of  the  trip  that  revolves  the  star  device  of  any  special  impor- 
tance. A  small  rod  clamped  to  the  shears  of  the  lathe  will  serve  the 
purpose  of  the  trip  as  well  as  the  more  convenient  device  shown  in  the 
sketch.  A  better  design  of  sliding-head  bar  has  a  continuous  rather 
than  intermittent  feed.  This  makes  a  more  expensive  device,  but  it 
does  better  work.  In  the  illustration  we  show  the  bar  arranged  for 
boring  a  tapering  hole,  but  the  description  applies  equally  well  when 
boring  a  parallel  hole. 

The  sliding-head  bar,  while  more  expensive  in  construction  than 
either  of  the  other  bars,  has  one  important  advantage.  If  required  to 
bore  a  long  hole,  or  indeed  any  hole,  with  the  fixed-head  bar,  the  bar 
must  be  at  least  twice  the  length  of  the  bore ;  if  the  sliding-head  bar  be 
used,  the  bar  need  be  only  the  length  of  the  bore  plus  a  small  addition 
for  clearance.  This  is  a  very  important  consideration;  for  if  the  work 
be  as  long  as  our  longest  lathe  will  admit,  the -bar  with  fixed  head  can 
not  be  used. 

Considerations  Governing  the  Number  of  Cutters. — The  single  and 
double  cutters  described  above  are  used  mainly  in  small  bores;  when  the 
hole  is  large  enough  to  use  a  fixed-head  bar  or  a  sliding-head  bar,  we 
then  generally  use  two  or  more  cutters.  We  use  a  number  of  cutters, 
not  because  two,  or  even  one,  would  be  impracticable,  but  because  a 
larger  number  of  cutters  is  more  economical  for  a  large  hole.  If  we  have 
to  bore  cylinders  3'  in  diameter,  the  work  done  by  each  cutter  will  be 
about  proportional  to  the  number  of  cutters;  and  if  one  cutter  be  used,  it 
may  wear  so  much  as  to  require  nearly  twice  as  long  to  do  the  work  as 
compared  with,  say,  a  dozen  cutters.  On  the  other  hand,  the  first  cost 
of  the  cutter-head  will  be  greater  for  the  larger  number  of  cutters.  We 
would  rarely  attempt,  however,  to  bore  so  large  a  cylinder  with  one  or 
two  cutters,  and  if  we  had  a  number  of  such  cylinders  to  bore,  the  final 
saving  would  be  more  than  sufficient  to  pay  for  the  extra  expense  in 
cutter-head  and  cutters. 

Methods  of  Driving  Boring-bar  in  Lathe  and  in  Boring-machine. — 
We  have  already  briefly  referred  to  the  method  of  driving  boring-bars  in 
the  lathe.  It  may  be  added  that  any  kind  of  clamp,  rod,  stud,  or  lathe- 
dog  secured  to  the  end  of  the  bar  and  engaging  with  the  face-plate  of 


THE  BORING-BAR  AND  ITS  USE  321 

the  lathe,  or  a  stud  projecting  from  same,  will  answer  the  purpose.  It  is 
well,  however,  especially  in  case  of  large  bores  and  heavy  cutting,  to 
have  the  bar  driven  from  opposite  sides.  This  may  be  readily  effected 
by  having  a  rod  pass  through  the  bal*  equally  on  opposite  sides  of  the  bar, 
in  contact  with  two  studs  or  other  projections  on  the  face-plate.  We 
shall  thus  get  a  balanced  drive,  which  does  not  tend  to  force  the  bar  from 
its  center. 

In  the  drilling-machine  and  horizontal  borer,  the  boring-bar  is  ordi- 
narily driven  by  a  key,  by  a  tang  on  the  end  of  the  bar,  or  by  a  threaded 
coupling.  In  the  first  case  the  bar  may  have  a  tapering  end  which  fits 
a  corresponding  taper  in  the  end  of  the  spindle  of  machine,  and  which 
is  held  by  a  key  passing  through  the  spindle  and  the  tapering  end  of  the 
bar.  In  the  second  case  also,  the  end  of  the  bar  is  tapering  and  fits  the 
tapering  hole  in  spindle,  but  instead  of  being  held  by  a  key  the  bar  is 
held  by  its  flattened  end  or  tang  fitting  a  corresponding  recess  in  the  bottom 
of  the  tapering  hole  in  spindle.  This  bar  is  illustrated  in  Fig.  455. 

The  third  method  is  illustrated  in  Fig.  461.  In  this  method  we  use 
a  threaded  coupling  or  sleeve,  one  end  of  which  screws  onto  the  end  of  the 
spindle  and  the  other  end  onto  the  threaded  end  of  the  boring-bar.  This 
plate  shows  also  a  means  of  securing  work  and  the  arrangement  for 
guiding  the  end  of  the  boring-bar.  The  method  illustrated  in  Fig.  455 
is  not  well  adapted  to  large  bars,  the  other  two  methods  being  better 
for  this  purpose. 

In  boring  a  large  hole  with  a  radial  drilling-machine  the  lathe  method 
of  driving  a  boring-bar  is  sometimes  employed.  For  this  purpose  we  use 
the  sliding-head  bar,  which  must  be  supported  on  centers,  the  same  as  in 
the  lathe.  One  of  these  centers  is  held  in  the  tapering  hole  of  the  drill- 
spindle  ;  the  other  may  be  held  directly  in  the  base-plate  of  the  machine, 
or  in  a  supplementary  plate  made  for  the  purpose.  Any  bar  other  than 
the  sliding-head  bar  cannot  be  used  in  this  way  in  the  drilling-machine. 

Feeding  Methods  Used  in  Connection  with  Boring-bars. — In  describ- 
ing the  boring-bar  in  general  it  has  been  necessary  to  mention  some  of 
the  ways  of  effecting  the  feed,  and  the  star  feed  has  been  described  in 
detail.  We  shall  now  describe  other  methods.  The  means  ordinarily 
used  in  the  lathe  is  the  common  feed  gearing  which  moves  the  carriage. 
In  this  case  the  work  is  generally,  though  not  invariably,  fastened  to  the 
carriage  and  travels  with  the  carriage,  and  the  bar  with  fixed  cutters  is 
used.  The  carriage-feed  is  used  also  in  a  case  like  that  illustrated  in 
Fig.  463.  In  this  sketch  the  work  is  shown  clamped  to  the  face-plate 
of  the  lathe,  and  a  modified  form  of  sliding  head  is  used,  but  neither  the 


322 


MACHINE-SHOP  TOOLS  AND  METHODS 


head  nor  the  bar  revolves.     A  key  may  be  used  to  keep  the  head  from 

turning,  and  the  bar  may  be  held  by  a  rod  passing  through  its  right  end. 

The  star  feed  is  not  used  in  connection  with  this  head,  the  feed  of 

the  head  being  effected  by  means  which  will  now  be  described.     The 


FIG.  463. 

sleeve  S  screws  into  the  head  H ,  and  with  the  head  slides  freely  on  the 
bar.  Two  slip  collars  lettered  K  are  secured  on  the  sleeve  S;  the  yoke  C 
fits  between  these  collars  and  has  a  U-shaped  opening  through  which  the 
sleeve  passes.  As  the  carriage  moves,  the  yoke,  being  held  in  the  tool- 
post  in  the  ordinary  manner,  engages  with  one  of  the  slip  collars  and  thus 
the  head  H  is  fed  lengthwise  of  the  bar.  This  sketch,  which  represents 
a  horizontal  section  through  the  work  and  lathe  face-plate,  shows  an 
arrangement  for  boring  a  tapering  hole,  but  the  same  mechanism  could 
be  used  in  boring  a  parallel  hole.  For  this  purpose  it  would  be  necessary 
to  move  the  tail-stock,  which  is  shown  set  off,  to  its  normal  position. 

When  boring  in  the  radial  drill  and  horizontal  boring  machine,  the  bar 
is  generally  fed  to  the  work.  The  feeding  mechanism  used  for  this 
purpose  is  nearly  similar  to  that  used  in  the  lathe,  and  it  is  more 
particularly  described  in  connection  with  descriptions  of  the  machines 
mentioned. 

Feeding  Laterally  with  Star  Feed. — As  used  in  boring,  the  star  feed 
has  been  sufficiently  described;  it  is  only  necessary  to  refer  to  its  use  in 


THE  BORING-BAR  AND  ITS  USE 


323 


lateral  feeding.  This  is  clearly  illustrated  in  Fig.  464,  which  shows  a  bar 
and  cutter-head  arranged  for  facing  the  flanges  of  an  engine  cylinder. 
Instead  of  the  head  having  direct  connection  with  the  bar,  it  slides  hi  a 
dove-tail  groove  planed  ki  the  fa$e  of  an  arm  projecting  from  the  bar. 
Passing  through  the  head  is  the  screw  with  star  fastened  on  its  extreme 


FIG.  464. 


FIG.  465. 


end.  As  the  bar  revolves  the  star  engages  with  some  fixed  projection, 
which  gives  an  intermittently  revolving  motion  to  the  screw,  and  thus 
feeds  the  head  bearing  the  cutter  radially  to  or  from  the  bar. 

The  part  here  referred  to  as  the  head  is  sometimes  called  the  tool- 
block;  when  thus  designated,  the  arm  and  tool-block  together  constitute 
the  head.  This  arm  is  generally  bored  out  to  fit  the  bar,  and  is  held  fast 
to  the  latter  by  a  key  or  by  set-screws.  Some  prefer  to  make  the  arm  with 
a  square  rather  than  with  a  round  hole,  and  have  it  parted  through  the 
center  of  the  hole  as  shown  in  Fig.  465.  This  not  only  admits  of  the  arm 
being  easily  detached  from  the  bar,  but  also  makes  it  adjustable,  within 
certain  limits,  to  different  sizes  of  bars.  The  arm  which  has  a  round  hole 
should  also  be  made  to  part  through  the  center  of  the  hole. 

The  sketch  in  Fig.  464  shows  an  engine-cylinder  which  is  assumed 
to  be  clamped  to  the  carriage  of  the  lathe,  and  to  have  been  bored  out 
by  either  a  fixed-head  bar  or  a  sliding-head  bar.  The  cutter-head  which 
has  just  been  described  is  used  for  machining  the  flanges  of  the  cylinder. 
Having  machined  the  faces  of  the  cylinder-flanges,  the  cutter  shown  in  the 
tool-block  is  removed  and  a  cutter  similar  to  that  shown  on  the  opposite 
end  of  the  cylinder  is  used  for  turning  the  edges  of  the  flanges.  When 
turning  these  edges  the  trip  that  operates  the  star  feed  is  dispensed  with, 
and  the  feed  is  effected  by  the  movement  of  the  lathe-carriage,  as  previ- 


324  MACHINE-SHOP  TOOLS  AND  METHODS 

ously  described.  The  cutter-head  must,  of  course,  be  moved  to  the  other 
end  of  the  bar  for  machining  the  opposite  end  of  the  cylinder. 

Boring  Tapering  Holes  with  Boring-bar. — When  boring  a  tapering 
hole  with  the  boring-bar  it  is  necessary  to  have  the  bar  arranged  at  an 
angle  to  the  axis  of  the  bore.  Fig.  457  illustrates  one  of  the  methods 
used.  This  view  shows  a  vertical  section  through  face-plate  of  lathe 
and  work,  the  latter  being  secured  to  the  lathe-carriage.  The  bar 
is  supported  at  the  tail-stock  end  in  the  ordinary  manner,  but  at  the 
head-stock  end  it  is  supported  by  an  auxiliary  center  held  in  the  face- 
plate. The  distance  between  this  auxiliary  center  and  the  center  of 
the  lathe-spindle  is  determined  by  the  taper  of  the  hole  to  be  bored. 
In  boring  a  tapering  hole  with  work  clamped  to  carriage  as  shown  in 
this  plate,  the  sliding-head  bar  is  the  right  bar  to  use.  Means  of  feed- 
ing the  cutters  of  this  bar  have  already  been  described.  It  is  sufficient 
to  observe  that  in  this  particular  case,  the  cutter  or  cutters  must  be 
on  one  side  of  the  bar  only.  Any  cutters  that  might  be  placed  opposite 
to  the  one  shown  would  have  no  contact  with  the  work,  and  would, 
therefore,  be  inoperative. 

A  tapering  hole  may  be  made  with  a  boring-bar  by  angling  the  bar 
at  the  tail-stock  end  of  the  lathe;  but  in  this  case  both  lathe-centers 
are  used  in  their  normal  position,  the  angularity  of  the  bar  being  effected 
by  securing  an  arm  to  the  bar  and  making  a  work-center  in  this  arm. 
In  this  method,  as  well  as  in  the  first  method  described  for  boring  taper- 
ing holes  with  the  bar,  the  work  is  supposed  to  be  clamped  to  the  lathe- 
carriage,  the  latter  being  held  in  a  stationary  position,  and  the  feed 
effected  by  movement  of  the  sliding  head.  As  in  the  previous  cases, 
the  taper  of  the  hole  is  determined  by  the  distance  between  the  normal 
center  in  the  bar  and  the  new  work-center  in  the  arm. 

Under  the  head  of  Feeding  Methods,  an  arrangement  for  boring  taper- 
ing holes  with  the  boring-bar  and  with  work  clamped  to  the  face-plate 
has  already  been  described.  This  arrangement  is  illustrated  in  Fig.  463. 
It  will  be  unnecessary  to  further  describe  this  method,  but  the  student 
should  observe  that  in  this  case  the  taper  is  effected  by  setting  off  the 
tail-stock. 

In  Fig.  466  *  is  shown  a  cutter-head  with  which  a  tapering  hole  may 
be  bored  without  offsetting  the  tail-stock.  In  this  case  the  head  itself 
is  tapering,  and  a  dovetailed  tool-block,  sliding  in  a  similarly  shaped 
groove,  carries  the  tool.  The  latter  is  fed  by  the  star-feed  mechanism. 
The  bar,  which  is  shown  broken  off  at  both  ends,  is  carried  on  the  lathe- 

*  Cut  taken  from  an  article  in  "American  Machinist,"  vol.  27,  page  529. 


THE  BORING-BAR  AND  ITS  USE 


325 


centers  in  line  with  the  lathe-spindle,  and  is  driven  by  a  lathe-dog  or 
otherwise.  The  head  does  not  slide  on  the  bar,  being  tightly  secured  to 
the  latter. 

Reboring  Engine-cylinders  Without  Removing  Same  from  Engine. — 
In  repairing  an  old  engine,  it  is  sometimes  cheaper  to  rebore  the  cylinder 


r\g  Tool  Holder 


Ajnerieav.  Machinist 


FIG.  466. 


in  its  place  than  to  take  it  to  the  shop.  Manufacturers  of  machine 
tools  furnish  an  elaborate  apparatus  for  this  purpose;  but  a  satisfactory 
device  may  be  improvised  as  follows:  Remove  the  piston,  one  or  both 
cylinder-heads,  and  sometimes  the  guides  from  the  engine,  and  adjust 
a  sliding-head  bar  in  the  cylinder,  concentric  with  the  counterbore.  One 
end  of  this  bar  may  be  held  in  the  stuffing-box — a  bushing  being  used 
if  necessary — the  other  end  being  supported  by  a  guide  bolted  across 
the  end  of  the  cylinder  by  means  of  the  studs. 

The  reason  we  adjust  the  bar  by  the  counterbore  is  that  this  part  of 
the  cylinder,  being  beyond  the  travel  of  the  piston,  and  larger  in  diameter 
than  the  normal  bore  of  the  cylinder,  cannot  wear  out  of  true.  When 
thus  bored,  the  original  alinement  of  the  cylinder  will  be  preserved, 
which  is  essential  to  the  smooth  working  of  the  engine. 

The  bar  may  be  operated  by  hand  in  connection  with  crank  and 
gearing,  or,  if  convenient  to  any  revolving  shaft,  it  may  be  operated 
by  power.  It  would  be  necessary  to  support  the  end  thrust  of  the  cut 
by  means  of  a  shoulder  or  slip-collar  on  the  bar.  In  the  more  elaborate 
apparatus  mentioned  above,  the  means  for  supporting  the  bar  and  the 
arrangement  for  holding  the  cutters  admit  of  adjustment  to  various 


326  MACHINE-SHOP  TOOLS  AND  METHODS 

sizes  of  cylinders.  The  gearing  is  also  more  complicated,  a  continuous 
feed  being  used  instead  of  the  intermittent.  In  some  designs  there  is 
provision  for  more  than  one  rate  of  feed,  but  this  can  also  be  effected 
in  the  star-feed  device  by  using  one  or  more  trips. 

Precautions  Necessary  in  Smooth-boring.  Causes  of  Chattering. — To 
insure  smooth-boring  the  boring-bar  should  be  as  short  and  as  rigid  as 
practicable,  and  the  cutters  should  be  held  rigidly  in  the  bar.  If  the 
feed  be  effected  by  the  movement  of  the  carriage,  there  should  be  no 
unnecessary  looseness  in  the  adjustment  in  the  carriage-gibs.  If  the 
sliding-head  bar  be  used  the  head  should  fit  the  bar,  and  the  feather  or 
key  which  prevents  the  head  from  turning  on  the  bar  should  be  as  close 
a  fit  as  practicable. 

The  instructions  which  have  been  given  respecting  rates  of  feed  in 
Chapter  XI  will  apply  to  boring-bar  work. 

For  taking  a  finishing  cut  the  cutter  should  generally  have  a  broad 
bearing  in  the  bore  and  be  fed  faster  than  when  taking  the  roughing  cut. 
But  when  the  broad  bearing  of  the  cutter  causes  chattering,  as  it  sometimes 
does  when  a  slender  bar  is  used,  it  may  be  necessary  to  reduce  the  bearing. 

One  of  the  principal  causes  of  chattering  is  too  much  heel  clearance  in 
the  cutter.  This  should  be  thoroughly  understood.  Failing  to  appre- 
ciate this,  and  giving  the  cutter  too  much  heel  clearance,  will  result 
not  only  in  rough  work  but  in  noisy  operation.  The  heel  clearance 
should  never  be  more  than  sufficient  for  smooth-cutting.  Reducing 
the  heel  clearance  will  sometimes  enable  us  to  increase  the  breadth  of 
cutter  contact  and  rate  of  feed. 

Shapes  of  Cutters. — Fig.  467  is  a  diagram  showing  cutters  placed 
at  various  angles  with  respect  to  radial  lines  through  the  axis  of  the 
boring-bar.  This  figure  also  shows  respectively  at  (1)  and  (2)  the  face 
views  of  roughing  and  finishing  cutters,  and  at  (3)  a  form  of  cutter  some- 
times used  when  the  slots  in  the  cutter-head  are  parallel  with  the  axis 
rather  than  at  right  angles.  No.  1  is  about  right  for  finishing  cuts  also  in 
such  metals  as  wrought  iron  and  steel.  It  will  be  seen  that  the  distance 
between  the  heel  of  each  cutter  and  the  circle  is  very  small,  and  that 
the  curve  of  the  heel  is  eccentric.  Sometimes  cutters  are  made  with 
no  clearance  at  this  point,  or  only  so  much  as  may  be  given  with  an  oil- 
stone. Such  cutters  cut  on  the  advancing  end  or  corner,  at  which  points 
they  must  have  clearance.  The  corner  of  the  cutters  should  be  well 
rounded,  as  shown  at  A.  To  get  the  best  results,  especially  with  cutters 
which  have  little  or  no  peripheral  clearance,  the  cutter  after  being  fitted 
to  the  head  or  to  the  bar  should  be  turned  in  the  lathe. 


THE  BORING-BAR  AND  ITS  USE 


327 


The  cutter  at  C,  if  well  fitted  and  supported  in,  a  heavy  bar,  will 
cut  wrought  iron  or  steel  very  well.  Under  similar  circumstances  it 
will  also  cut  cast  iron,  although  it  is  not  usually  considered  necessary 
to  have  so  much  rake  for  -this  metal.  But,  if  the  bar  be  of  small  diameter 
in  proportion  to  its  length,  or  the  cutters  project  far  beyond  their  sup- 


ROUGHING  CUTTER 


FINISHING  CUTTER 


FIG.  467. 

port,  cutters  placed  as  at  C  would  be  likely  to  cause  jar  and  chatter. 
Under  the  unfavorable  conditions  referred  to,  and  indeed  under  average 
conditions,  the  cutter  is  likely  to  do  smoother  work  when  made  with  little 
rake,  as  at  C  1,  or  with  no  rake.  In  boring  brass,  and  in  some  cases  of 
boring  cast  iron  when  it  seems  difficult  to  overcome  the  chatter  in  any 
other  way,  the  tool  may  be  given  negative  rake,  as  in  C  2. 

The  causes  of  chattering  are  various,  and  only  the  leading  causes 
have  been  mentioned.  Sometimes  the  difficulty  may  be  overcome 
by  placing  a  piece  of  leather  or  waste  between  the  tail  of  the  dog  and  the 
face-plate  or  stud  by  which  it  is  driven. 

The  wear  of  the  boring-bar  centers  may,  by  causing  looseness  of 
the  boring-bar  between  the  lathe  centers,  cause  chattering.  Boring- 
bar  centers  should  therefore  have  ample  bearing.  Large  cast-iron  bor- 
ing-bars should  be  made  with  steel  plugs  for  the  centers  and  oil-holes 
should  be  provided  for  oiling  the  center  without  loosening  the  tail-spindle. 

Boring-bar  cutters  should  be  tempered  about  the  same  as  other 
lathe-tools. 


CHAPTER  XXI 

HORIZONTAL   BORING-  AND   DRILLING-MACHINES   AND   WORK. 
CRANK-BORING  MACHINE 

Description  of  Typical  Machines. — The  horizontal  boring-machine 
shown  in  Fig.  468  is  designed  mainly  to  enlarge  and  finish  holes,  as,  for 
example,  the  boring  of  bracket-boxes,  pillow-blocks,  etc.  It  will  also 
drill  holes  from  the  solid.  The  bed  B,  head-stock  H,  table-support  T  1, 
and  yoke  Y  comprise  the  main  framework  of  the  machine.  The  spindle 
S  is  driven  by  pulley  P  and  back-gearing  G  as  in  a  lathe.  It  is  fed 
lengthwise  by  cone  pulleys  P  2  and  other  mechanism  not  shown  in  the 
cut.  The  hand-wheel  H  I  gives  the  hand-feed.  The  table  T  is  adjusted 
crosswise  and  lengthwise  by  the  shaft  S  2  and  crank  H  2.  The  vertical 
movement  is  effected  by  means  of  gearing  and  shafts  S  3  and  S  4,  which 
operate  the  screws  S  1  and  S  5.  The  power  for  this  purpose  is  applied 
by  a  hand-crank.  The  longitudinal  movement  of  the  table  is  26".  The 
traverse  of  the  spindle  in  a  machine  of  this  (medium)  size  is  sufficient  to 
bore  a  hole  20"  long. 

The  work  is  bolted  to  the  table  T,  and  is  adjusted  in  line  with  S 
by  the  movement  of  the  table  as  described.  The  boring-bar  is  then 
placed. in  position  in  the  yoke  and  secured  to  the  spindle  by  a  key,  one 
end  of  the  bar  being  shaped  to  fit  the  hole  in  end  of  spindle  S.  (In 
some  work  the  spindle  S  is  used  as  a  boring-bar.)  The  cutters  in  the 
bar  are  next  adjusted  and  the  bar  fed  through  the  work  by  the  feed 
mechanism  above  described. 

This  is  a  very  convenient  machine  for  boring  cylinders,  hangers, 
small  framework,  etc.  By  using  a  suitable  attachment  for  guiding  the 
end  of  the  bar  much  of  the  work  done  on  this  machine  could  be  done 
on  a  radial  drill,  though  not  so  conveniently  and  quickly. 

Fig.  469  shows  the  "  Binsse "  machine  of  this  class.  It  will  be  seen 
that  the  cone  pulley  is  not  placed  on  the  main  spindle  in  this  machine. 
The  speed  changes  are  made  by  a  lever  L  shown  behind  the  large 
driving-gear.  A  motion  to  the  left  gives  the  quick-speed  series,  a 

328 


330 


MACHINE-SHOP  TOOLS  AND  METHODS 


contrary  movement  engages  the  slow  or  back-gear  speeds,  and  the  inter- 
mediate position  of  the  lever  stops  the  rotation  of  the  bar. 


FIG.  469. 


The  Feeds. — These  machines  are  made  in  both  gear-  and  friction-feeds. 
The  illustration  shows  the  machine  having  friction-feed.     Motion  is  trans- 


,, 


FIG.  470. 

mitted  to  the  friction-disks  F,  F  1,  and  F2  by  the  gears  G.  On  the 
worm-shaft  S  1  is  a  worm  engaging  with  a  worm-wheel.  The  shaft 
of  the  latter  gives  a  traversing  motion  to  S  by  mechanism  not  shown. 


HORIZONTAL  BORING-  AND  DRILLING-MACHINES  331 

This  mechanism  may  consist  of  either  two  bevel-gears  operating  a  screw 
passing  through  a  threaded  nut  in  AC,  or  a  rack  and  pinion,  the  rack  be- 
ing bolted  to  the  under  side  of  N.  *  The  feed  may  be  changed  by  raising 
or  lowering  the  disks  F  l.-r 

The  Work. — Fig.  470  shows  a  casting  in  one  of  these  machines 
secured  to  an  angle-plate  and  ready  to  be  roughed  out  with  a  three-lip 
drill.  When  the  drilling  is  completed  the  hole  may  be  reamed  to  final 
size.  More  accurate  work,  however,  may  be  done  by  " truing"  up 
the  hole  with  a  boring-bar  before  using  the  reamer. 

Fig.  471  shows  a  casting  in  which  three  small  holes  are  to  be  bored 
at  each  end.  For  this  purpose  a  small  bar  is  inserted  in  the  socket  of 


FIG.  471. 

the  main  spindle  and  a  reducing  bushing  is  used  in  the  yoke.  Hav- 
ing bored  the  upper  holes,  the  bar  is  removed  and  the  table  adjusted  to 
bring  the  work  into  alinement  for  the  next  two  holes.  The  screws 
controlling  the  table  movements  in  these  machines  are  furnished  with 
index-dials  reading  to  thousandths  of  an  inch.  These  dials  are  of 
value  in  work  of  the  above  character  or  in  any  other  work  where 
accurate  spacing  of  the  holes  is  required.  For  work  requiring  a  higher 
degree  of  accuracy,  such  as  fine  jig-work,  etc.,  a  precision  cross- feed  screw 
is  furnished. 

The  Facing  Attachment  shown  in  Fig.  472  is  parted  in  the  middle 


332 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  its  bore,  and  it  may  be  readily  secured  by  the  two  bolts  and  a  key 
in  any  position  lengthwise  of  the  bar.  The  cutter  is  held  at  C,  being 
clamped  by  the  nut  N  1,  and  it  is  fed  radially  by  the  star  feed  shown. 


'  Nl 


FIG.  472. 


In  Fig.  473  a  slightly  different  facing  attachment  is  shown  in  opera- 
tion.    In  this  particular  case  the  bar  and  yoke  cannot  be  used,  and  the 


FIG.  473. 

attachment  is  carried  on  the  end  of  the  spindle.  Ordinarily  the  bar 
may  pass  through  the  work,  and  when  necessary  the  attachment  may 
be  reversed  and  the  opposite  end  of  the  work  faced. 


HORIZONTAL  BORING-  AND  DRILLING-MACHINES 


333 


Miscellaneous  Work  with  the  Facing  Attachment. — The  author  of 
this  work  has  used  a  facing-head  in  a  horizontal  boring-machine  for  a 


FIG.  474. 

great  variety  of  interior  and  exterior  turning.  With  a  tool  similar  to 
the  boring-tool  used  in  the  tool-post  of  a  lathe,  shallow  holes  may  be 
bored  to  size  or  merely  "  trued  up"  preparatory  to  the  use  of  the  reamer, 
and  with  a  thread-tool  interior  threads  may  be  cut.  Also  with  suit- 
able tools  various  shapes  of  turning 
may  be  performed  on  hubs,  includ- 
ing thread-cutting. 

Fig.  474  shows  a  boring-head 
for  large  holes.  This  is  secured  to  ' 
the  bar  by  a  key  or  bolted  to  a 
face-plate  on  the  bar.  The  cutters 
are  adjusted  by  the  screws  and 
held  by  the  straps  as  shgwn. 

Rotary  Tables. — These  tables 
provide  a  means  by  which  holes 
radiating  from  a  common  center 

may  be  drilled  or  bored.  They  are  fitted  to  the  cross-feed  table  or 
carriage  as  shown  in  Fig.  475.  The  one  in  the  figure  is  graduated  for 
180°  of  movement. 

Milling  in  the  Horizontal  Borer. — When  supplied  with  either  hand 
or  power  cross-feed  the  horizontal  boring-machine  may  be  used  as  a 
miller.  Fig.  476  shows  a  large  drum  mounted  on  indexing  centers.  It  is 


FIG.  475. 


334 


MACHINE-SHOP  TOOLS  AND  METHODS 


required  to  mill  four  deep  slots  in  the  drum.     Having  milled  the  first 
slot  as  shown,  the  drum  is  turned  through  90°  by  the  indexing  mechan- 


FIG.  476. 

ism  and  the  next  slot  milled,  etc.  This  illustration  shows  only  one 
method,  but  it  is  obvious  that  face-mills,  end-mills,  and  other  milling- 
cutters  may  be  secured  to  the  end  of  the  spindle  or  on  the  bar  and 
used  on  any  work  to  which  the  cutters  are  adapted. 

Base-boring  and  Drilling  Machines. — In  Figs.  477  to  480  inclusive 
is  described  a  class  of  machines  which,  in  order  to  distinguish  them 
from  the  foregoing,  we  shall  call  base-boring  machines.  These 
machines  are  especially  adapted  to  heavy  framework,  and  this  work 
is  usually  secured  to  the  low  base-plate  of  the  boring-machine.  There 
is  considerable  variation  in  the  design  of  these  machines,  and  in  some 
of  them  tapping  and  milling  may  be  done  as  well  as  drilling  and  boring. 
Fig.  477  is  a  perspective  view  of  one  of  these  machines  and  Fig.  478 
shows  the  machine  engaged  in  boring  two  large  frame  castings.  These 
castings  are  bolted  together  in  connection  with  their  cross-girts,  and 
in  boring  the  two  together  more  accurate  alinement  may  be  obtained 
than  if  they  were  bored  separately. 
,;  In  Fig.  479  is  shown  the  same  machine  milling  T  slots  in  the  table 


HORIZONTAL  BORING-  AND  DRILLING-MACHINES  335 


FIG.  477. 


FIG.  478. 


336  MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  479. 


FIG.  480. 


338 


MACHINE-SHOP  TOOLS  AND  METHODS 


of  some  machine.  For  this  work  two  milling-cutters  are  required.  First 
a  rectangular  slot  of  the  full  depth  is  cut  with  an  end-mill.  The  under 
cutting  is  next  done  with  a  mill  of  the  required  shape. 


FIG.  482. 

Machining  a  Flanged  Cylinder. — The  usual  method  of  securing  a 
plain  cylinder  to  a  machine-tool  table  is  clearly  shown  in  Fig.  480.  In 
this  case  the  flanges  of  the  cylinder  are  to  be  faced,  drilled,  and  tapped 
at  one  chucking.  Two  stout  timbers  upon  which  the  cylinder  is  to 
rest  are  shaped  to  fit  the  cylinder.  Two  shorter  pieces  are  similarly 
shaped  and  used  as  straps  to  hold  the  cylinder  down.  In  some  cases 
the  timbers,  having  been  cut  out  to  the  approximate  shape,  are  bored 
out  to  fit  the  cylinder  while  strapped  to  the  boring-machine  base- 


FIG    4X3. 


339 


340  MACHINE-SHOP  TOOLS  AND   METHODS 

plate,  or  table.  This  method  facilitates  the  accurate  alinement  of  the 
cylinder  in  the  boring-machine.  The  use  of  a  wooden  fixture  is  very 
desirable  in  clamping  frail  cylinders,  the  elasticity  of  the  wood  com- 
pensating for  any  irregularity  there  may  be  in  the  periphery  of  the 
cylinder.  When  a  large  number  of  cylinders  are  to  be  machined,  a 
special  cast-iron  fixture  is  generally  used;  but  in  the  case  of  frail  work 
the  fixture  must  be  adjusted  with  delicacy  and  skill  to  avoid  distorting 
the  cylinder.  The  latter  precaution  is  of  especial  importance  in  boring  a 
cylinder. 

The  machines  described  in  connection  with  the  three  preceding 
illustrations  are  designed  for  a  large  variety  of  work.  Both  heads  are 
adjustable  vertically  on  the  standards,  and  both  standards  are  adjusta- 
ble lengthwise  on  the  base.  The  left  standard  is  also  adjustable  to 
and  from  the  right-hand  standard.  These  machines  have  the  usual 
automatic  and  hand  feeds. 

Special  Boring-  and  Facing-machine. — In  Fig.  481  we  show  a  machine 
designed  especially  for  boring  and  facing  gun-hoops.  It  is  evident, 
however,  that  other  cylindrical  work  can  be  bored  as  well.  In  addi- 
tion to  various  sizes  of  interchangeable  cutter-heads  the  machine  has 
two  facing-heads.  These  facing-heads  are  carried  on  revolving-sleeves 
in  the  head-stock  and  tail-stock.  The  driving  mechanism  consists  of 
the  cone  pulley  and  gearing  on  the  left.  The  machine  has  the  usual 
hand  and  automatic  feed,  the  latter  consisting  of  the  cone  pulleys  and 
gearing  shown  at  the  right. 

The  special  fixtures  used  for  holding  cylinders  are  constructed  on 
practically  the  same  principle  as  a  steady  rest  used  in  the  lathe.  In 
this  machine  two  steady  rests  are  used  instead  of  a  special  fixture. 

Portable  Boring-,  Drilling-,  and  Milling-machines. — These  machines, 
one  of  which  is  shown  in  Fig.  482,  are  designed  to  be  used  in  connection 
with  a  large  base-plate  and  bolted  in  different  positions  on  the  plate 
instead  of  moving  the  work.  This  is  advantageous  in  very  heavy  work. 
Being  electrically  driven,  these  machines  are  independent  of  the  main 
shaft.  The  column  swivels  on  a  graduated  base  and  the  whole  machine 
may  be  fed  along  a  short  distance  on  its  sub-base  without  slackening 
the  bolts  which  secure  it  to  the  floor-plate. 

Boring-machines  somewhat  similar  to  the  above  are  made  with  a 
head  which  swivels  in  a  vertical  plane  in  addition  to  the  swiveling  base. 
These  are  Universal  boring-,  drilling-,  and  milling-machines. 


CRANK-BORING   MACHINE  341 


CRANK-BORING   MACHINE 

A  good  example  of  the  crank-boring  machine  is  shown  in  Fig.  483. 
As  will  be  seen  the  spindle  is  vertical.  On  the  lower  end  of  the  spindle 
is  a  cutter-head  carrying  three  cutters.  The  cutters  bore  the  shaft-holes 
and  crank-pin  holes  in  large  crank-arms  by  making  a  circular  groove 
which  releases  the  central  core.  This  is  very  much  quicker  than 
making  chips  of  all  the  material  removed.  When  facing  is  to  be  done 
the  head  on  the  spindle  is  replaced  by  the  one  on  the  floor. 

Holes  as  small  as  2"  in  diameter  are  sometimes  made  with  cutters 
arranged  somewhat  similar  to  the  method  described  above.  There  is, 
however,  this  difference:  a  hole  about  3/V'  diameter  is  first  drilled  and 
the  small  cutter-head  is  made  with  a  central  pin  or  pilot  which  is  guided 
by  the  small  hole  in  the  same  manner  that  a  pin-drill  is  guided.  With 
this  device  the  core  removed  is  in  the  form  of  a  hollow  cylinder  or  ring. 
The  tool  is  not  adapted  to  drilling  deep  holes,  but  large  holes  may  be 
drilled  deeper  because  the  cutters  may  be  stronger. 

Large  cylinders  for  vertical  engines  are  usually  bored  in  a  vertical 
boring-mill  designed  especially  for  such  work.  If  bored  in  a  horizontal 
machine  the  deflection  of  the  cylinder-walls  might  cause  the  cylinder  to 
be  "out  of  round"  when  set  on  its  permanent  foundation.  In  1882  the 
cylinder  for  the  steamer  Pilgrim  was  bored  at  the  Morgan  Iron  Works  in 
New  York,  where  the  writer  was  then  employed.  This  cylinder  was  110" 
diameter  by  14'  stroke.  It  was  bored  in  a  vertical  machine  with  a 
sliding-head  bar. 


CHAPTER  XXII 
VERTICAL   BORING-   AND    TURNING-MILLS,    TOOLS   AND   WORK 

Advantage  of  the  Machine  in  Turning  Heavy  Work. — In  the  hori- 
zontal boring-  and  drilling-machine  and  in  the  upright  drill  the  tool 
(with  rare  exceptions)  revolves  and  the  work  is  stationary.  In  the 
vertical  boring-  and  turning-mill  the  work  revolves  while  the  tool  is 
stationary — at  least  the  tool  does  not  revolve.  The  last-named  machine 
is  in  reality  a  lathe,  and  could  with  propriety  be  called  a  vertical-spindle 
lathe.  It  is  designed  to  do  about  the  same  class  of  work  as  is  done  on 
some  short  chucking-lathes,  and  is  better  adapted  to  such  work,  as  we 
shall  presently  show.  Fig.  484  shows  a  37"  Bullard  boring-  and  turning- 
mill.  The  table  T  serves  the  same  purpose  as  the  face-plate  of  a  lathe, 
the  work  being  secured  to  the  table  by  straps  and  bolts,  as  shown  in  Fig. 
484,  or  by  a  chuck,  as  shown  in  Fig.  485.  In  the  first  figure  the  machine 
is  shown  facing  a  boring-mill  saddle  and  turning  the  edge,  both  tools 
being  used,  while  in  the  second  illustration  the  operation  is  that  of 
turning  the  inner  and  outer  diameters  of  a  cylindrical  shell.  The  machines 
shown  in  these  two  illustrations  are  designed  for  comparatively  small 
work,  but  when  we  consider  that  the  larger  machines  of  this  class  will 
handle  work  of  many  tons  weight,  the  advantage  of  the  horizontal  table 
or  face-plate  will  be  apparent.  Thus,  in  securing  an  engine  fly-wheel 
weighing,  say,  ten  tons,  to  the  vertical  face-plate  of  a  lathe,  it  is  necessary 
to  support  this  weight  independently  of  the  face-plate  during  the  time 
of  adjusting  the  work.  If  the  same  fly-wheel  were  turned  in  a  vertical 
boring-  and  turning-mill  its  weight  would  be  supported  by  the  horizontal 
table,  and  for  this  reason  it  cpuld  be  more  quickly  adjusted  concentric 
with  the  spindle  of  the  machine.  Another  advantage  of  the  latter 
machine  is  that  the  weight  of  the  revolving  mass  does  not  tend  to  wear 
the  spindle  out  of  correct  alinement,  as  it  does  in  the  ordinary  lathe. 

Fig.  486  shows  a  sectional  view  of  the  table  and  spindle  of  the  machine 
illustrated  in  Fig.  484.  The  weight  is  supported  on  the  angular  bearing 
B>  and  the  spindle  is  held  to  its  bearing  by  the  adjusting-nut  N. 

342 


VERTICAL  BORING-  AND  TURNING-MILLS 


343 


In  Fig.  487  is  shown  a  rear  view  of  the  same  machine  as  arranged 
to  be  driven  by  a  constant-speed  motor.     Power  is  transmitted  from  the 


FIG.  484. 


motor  to  the  cone-pulley  shaft  by  a  Renold  silent  chain.     We  may  say 
by  way  of  parenthesis  that  this  chain  furnishes  a  very  efficient  and 


344 


MACHINE-SHOP  TOOLS  AND  METHODS 


satisfactory  drive.    The  lower  cone-pulley  P  is  connected  to  the  upper 
bv  a  leather  belt.     On  the  same  shaft  with  the  lower  cone  pulley  is  a 


1'iG.  485. 


bevel-gear  G  meshing  with  the  bevel-gear  G  1.     The  latter  drives  the 
table  through  the  reducing  gears  shown,  the  last  gear  in  this  train  being 


VERTICAL  BORING-  AND  TURNING-MILLS 


345 


the  bevel-gear  G2,  which  meshes  with  a  large  gear  on  the  under  side 
of  the  table. 


FIG.  486. 

Fig.  488  shows  a  complete  front  view  of  the  37"  machine.    The 
two  side-castings  H,  called  the  housing,  are  bolted  to  the  bed  B  and 


346 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  whole  is  supported  on  a  foundation  of  masonry.     Movable  vertically 
on  the  housing  is  the  cross-rail  R  carrying  the  two  heads  H  1.    Both  of 


FIG.  487. 

these  move  on  R,  and  each  carries  a  tool-holder  T.    The  vertical  slides 
have  vertical  movement  and  angular  movement  in  a  vertical  plane. 


VERTICAL  BORING-  AND   TURNING-MILLS 


347 


They  are  fed  automatically  by  the  feed-gearing  G  3,  screw  S,  and  rod  R  I. 
They  may  also  be  operated  by  hand-cranks  shown.     The  table  T,  to 


FIG.  488. 


which  the  work  is  bolted,  is  operated  by  cone  pulleys  P  and  gearing 
described  in  connection  with  Fig.  487. 


348 


MACHINE-SHOP  TOOLS  AND  METHODS 


Each  of  the  two  tool-heads  may  be  moved  to  a  central  position  over 
the  table,  the  vertical  slides  being  bored  to  receive  boring-bars  in  this 


FIG.  489. 


position.    The  table  is  also  bored  to  receive  bushings  to  fit  different  sizes 
of  bars.     By  this  arrangement  a  boring-bar  may  be  supported  at  each 


VERTICAL  BORING-  AND  TURNING-MILLS 


349 


end,  and  this  makes  it  a  great  deal  stiffer  for  taking  heavy  cuts.     Large 
reamers,  drills,  etc.,  may  also  be  heki  in  the  vertical  slide.    To  receive 


FIG.  490. 


small  drills  and  reamers,  the  tool-post  is  bored  to  the  Morse  taper,  and 
these  smaller  tools  may  be  used  without  removing  the  tool-post  from  the 


350 


MACHINE-SHOP  TOOLS  AND  METHODS 


slide.  In  drilling  and  reaming  each  of  the  heads  may  be  moved  up 
against  a  fixed  stop.  This  stop  brings  the  drill  or  reamer  into  exact 
alinement  with  the  center  of  the  table. 


FIG.  491. 


This  machine  appears  to  have  some  one  of  the  modern  "cone-of- 
gears"  feeding  systems.    The  feed  has  ten  changes  ranging  from  i/32 


VERTICAL   BORING-  AND  TURNING-MILLS 


351 


to   3/4    inch  horizontally,  and  from  l/50  to  l/2  inch    in   angular  and 
vertical  directions. 


FIG.  492. 


The  Tools. — In  Fig.  489  we  show  some  of  the  tools  used  in  a  vertical 
boring-  and  turning-mill.     The  names  of  these  tools  are  as  follows:  No.  1, 


352 


MACHINE-SHOP  TOOLS  AND  METHODS 


tool-holder;  No.  2,  boring-bar;  No.  3,  hog-nose  turning-tool;  No.  4, 
wide  finishing-tool;  No.  5,  round-nose  tool;  No.  6,  side  finishing-tool; 
No.  7  boring-tool;  No.  8,  cutters  for  boring-bar. 


FIG.  493. 

In  Fig.  490  is  shown  a  method  of  bracing  a  high  casting,  and  in 
Fig.  491  we  show  how  the  angle-plate  may  be  used  in  holding  work  having 
a  face  at  right  angles  to  the  surface  to  be  machined. 

In  roughing-out  a  casting  with  a  broad  tool  it  is  often  advantageous 
to  notch  the  cutting-edge  of  the  tool  as  was  explained  in  connection 


VERTICAL  BORING-  AND  TURNING-MILLS 

with  Fig.  203.  In  Fig.  492  we  show  the  principle  as  used  on  work  in  a 
vertical  boring-  and  turning-mill,  a  notched  tool  being  shown  at  the 
right  and  a  plain  tool  at  the  left. 

The  boring-mills  described  irfthis  chapter  are  of  small  size.     The 


FIG.  494. 

same  manufacturers,  however,  make  them  also  in  large  sizes.     Some 
machines  are  made  smaller  and  with  only  one  tool-head. 

Special  Boring-mills  for  Car-wheels. — A  boring-mill  designed  espe- 
cially for  car-wheels  is  shown  in  Fig.  493.  This  machine  carries  a 
universal  chuck  in  connection  with  the  table.  The  jaws  of  this  chuck 
fit  under  the  flange  of  the  wheel  in  such  a  manner  that  by  one  movement 
of  the  chuck-wrench  the  car-wheels  are  chucked  true.  Attached  to  the 
machine  is  a  hoisting  device  for  lifting  the  car-wheels  on  and  off.  The 
boring-bar  is  counterbalanced,  as  boring-bars  are  in  all  vertical  boring- 
mills.  This  machine  is  for  boring  and  facing  the  hubs  only. 


354 


MACHINE-SHOP  TOOLS  AND  METHODS 


Turret-heads  on  Vertical  Boring-  and  Turning-mills. — The  turret 
principle,  which  has  been  described  in  connection  with  other  machines 


FIG.  495. 

in  this  book,  is  used  also  on  vertical  boring-  and  turning-mills.     In 
Fig.  494  is  shown  a  five-tool  turret  as  applied  to  machines  of  this  class. 


VERTICAL  BORING-  AND  TURNING-MILLS  355 

In  machining  a  pulley,  for  instance,  all  the  tools  for  this  work,  including 
the  reamer  for  the  bore,  could  be  held  in  the  turret-head.  In  Fig.  495 
we  show  several  tools  used  in  connection  with  the  turret-head,  the  names 
of  which  are  as  follows*  No.  1,  four-lip  drill;  No.  2,  boring-bar;  No.  3, 
sectional  view  of  adjustable  reamer  with  floating  shank;  *  No.  4,  perspec- 
tive view  of  same  reamer,  and  No.  5,  limit-gage. 

Vertical  boring-  and  turning-mills  can  be  furnished  with  gearing 
for  cutting  thread.  The  turret-machine  shown  in  Fig.  494  is  provided 
with  thread-cutting  mechanism,  and  the  driving-  and  feeding-gears, 
which  are  of  novel  design,  are  fully  described  in  vol.  27,  pages  116-118, 
of  the  "American  Machinist." 

*  The  shank  end  of  the  floating-shank  reamer  is  so  constructed  as  to  admit  of 
a  small  degree  of  looseness  or  freedom,  the  object  being  to  compensate  for  a  pos- 
sible error  in  the  alinement  of  the  machine. 


CHAPTER  XXIII 
PLANERS  AND  SHAPERS  AND  PLANER  AND  SHAPER  WORK 

The  Metal  Planer. — In  Fig.  496,  which  shows  a  typical  metal  planer, 
B  is  the  bed,  T  the  work-table,  R  the  cross-rail,  C  the  cross-head  carry- 
ing tool-slide  S  and  tool-block  T  1,  H  I  the  housing,  and  P,  PI,  P  2, 
P  3  tight  and  loose  pulleys  on  driving-shaft.  The  housing  castings  H 1 
are  bolted  on  either  side  of  the  bed  B.  Cross-rail  R  is  movable  vertically 
on  the  housing  by  a  crank  on  shaft  H,  which  shaft  operates,  through 
the  gears  G  2,  two  screws  passing  through  threaded  lugs  on  R.  Cross- 
head  C  has  automatic  movement  on  R  by  feed-disk  Z),  feed-gearing  Fy 
and  rack  F  1.  The  slide  S  may  be  clamped  on  C  at  any  angle  in  the  ver- 
tical plane,  and  when  so  clamped  may  be  fed  automatically  by  the 
feed  mechanism  noted. 

Feed-disk. — Fig.  497  shows  a  sectional  view  of  a  feed-disk  similar 
in  principle  to  the  one  on  this  machine.  A  side  elevation  of  the  disk 
and  its  accompanying  mechanism  is  shown  in  Fig.  498.  The  shaft 
S  3  in  Fig.  497  is  driven  by  gearing,  and  its  motion  is  reversed  when 
the  planer-bed  reverses.  Integral  with  S  3  is  flange  F  2.  The  disk  D 
is  in  two  parts,  D  and  D  1,  and  these  are  held  together  on  F  2  by  the 
screws  S  4.  Between  F  2  and  the  disc  are  the  two  leather  washers 
shown.  Now  when  S  3  revolves,  D  is  caused  to  revolve  with  it  by  fric- 
tion between  the  leather  and  the  disks.  Being  driven  by  friction,  which 
may  be  increased  or  diminished  by  the  screws  S  4,  the  disk  D  may  be 
stopped  independently  of  S  3.  While  S  3  makes  a  number  of  revolu- 
tions, depending  upon  the  length  of  table-stroke,  D  always  makes  less 
than  one  revolution.  The  motion  of  D  is  limited  by  S  5  operating 
between  two  fixed  projections  on  the  side  of  the  housing.  Referring 
back  to  Fig.  496,  while  D  always  moves  the  same,  the  feed  may  be 
varied  by  moving  B  I  nearer  to  or  farther  from  the  center  of  the  disk. 
For  this  purpose  knob  K,  in  connection  with  the  screw  S,  shown  in  Fig. 
498,  is  used. 

Feed-gearing  in  Cross-head. — The  immediate  connection  of  the  feed 
mechanism  with  C  and  S  is  made  by  the  screw  S  1  and  feed-rod  F  3. 

356 


PLANERS  AND  SHAPERS 


357 


This  will  be  more  clearly  understood  by  reference  to  the  sectional  view, 
Fig.  499.    This  figure  shows  a  vertical  section  through  center  of  C,  S, 


/ 


.,.— 


and  T  1 .  It  will  be  seen  that  S  1  passes  through  a  threaded  lug  fastened 
on  C.  F  3  drives  the  miter  gear  G  3  by  means  of  a  feather  key,  which 
permits  G  3  to  slide  on  F  3.  Meshing  with  G  3  is  the  miter  gear  G  4, 
operating  the  screw  S  2  by  means  of  gears  G  5  and  G  6.  When  S  2  is 


358 


MACHINE-SHOP  TOOLS  AND  METHODS 


C1 


D1 


FIG.  498. 


PLANERS  AND  SHAPERS 


359 


in  operation  it  causes  the  slide  S  to  move  up  or  down,  depending  on 
whether  the  pawl  P  4  (Fig.  498)  is^in  forward  or  reverse  connection  with 
its  ratchet-wheel  F  4.  Cross-head  C  (Fig.  499)  may  be  fed  independ- 


FIG.  499. 

ently  of  S  and  vice  versa,  and  by  placing  the  pawl  in  a  neutral  position, 
as  shown  in  Fig.  498,  both  feeds  may  be  disengaged. 

Table  Movement,  etc.— The  table  T  (Fig.  496)  traverses  the  bed 
backward  and  forward,  being  guided  in  the  V-shaped  ways  V.  The 
work  is  secured  to  the  table,  and  for  each  stroke  of  the  table  the  cross- 
head  C,  carrying  the  cutting-tool,  is  fed  a  distance  of  from  about  1/64 
to  l/2  inch,  depending  upon  the  nature  of  the  work.  The  movement  of 
the  table  toward  the  tool  is  effected  by  an  open  belt  which  runs  on  the 
pulleys  P  and  P  1  (Fig.  500) .  The  first  of  these  pulleys  runs  loosely 
and  the  other  is  tight  on  shaft  £4.  On  the  same  shaft  are  two  other 


360 


MACHINE-SHOP  TOOLS  AND  METHODS 


pulleys,  tight  and  loose,  with  a  crossed  belt.     When  the  table  reaches 
the  end  of  its  stroke  the  belts  are  automatically  shifted,  so  that  the  belts 


FIG.  500. 


which  were  on  the  tight  and  loose  pulleys  P  1  and  P  2  are  now  on  P 
and  P  3.     In  other  words,  when  the  open  belt  is  driving  the  table  for- 


C 


Rack 


uui 


G11 


FIG.  501. 

ward  the  cross-belt  is  running  idly  on  P2.  and  when  the  cross-belt  is 
running  the  table  backward  the  open  belt  is  running  idly  on  P. 
Keyed  to  S  4  is  pinion  G  8.  This  gear,  with  its  connecting-gears  G  9 


PLANERS  AND  SHAPERS 


361 


and  G  10,  gives  motion  to  the  large  gear  Gil,  which  meshes  with  a 
rack  on  the  under  side  of  the  table.  A  side  view  of  this  larger  gear, 
with  a  section  of  the  table,  is  shown  in  Fig.  501. 

Referring  again  to  Fig.  496,  the  belts  are  caused  to  shift  by  the 
dogs  or  tappets  D  I  engaging  with  lever  L.  L  is  connected  to  the 
belts  by  a  system  of  levers  not  clearly  shown.  As  the  tool  does  not  cut 
on  the  reverse  stroke  the  table  traverses  several  times  faster  on  the 
reverse  stroke  than  on  the  forward. 

"  Second-belt  Planer-drive." — Fig.  502  shows  a  planer  the  driving- 
gear  of  which  is  a  departure  from  ordinary  construction.  It  will  be 


FIG.  502. 

noticed  that  in  place  of  the  two  gears  usually  seen  on  the  rear  side  of 
the  planer,  this  machine  has  a  short  open  belt.  The  connection  of  this 
belt  with  the  other  elements  of  the  driving-gear  is  clearly  shown  in 
Fig.  503.  From  the  three  driving-pulleys  K,  upon  which  the  usual 
narrow  shifting  belts  are  employed,  it  is  easy  to  follow  the  driving 
mechanism  up  to  the  pinion  J  which  engages  directly  with  the  bed- 
rack.  The  tension  of  the  belt  E  is  maintained  by  the  weight  B  as  shown. 
The  principal  claim  of  the  manufacturers  is  softness  of  action,  due  to 
the  substitution  of  a  belt  in  place  of  high-speed  gears.  This  softness 
of  action  they  say  "assists  greatly  in  turning  off  smooth,  finely  finished 


362 


MACHINE-SHOP  TOOLS  AND  METHODS 


work,"  and  at  the  same  time  admits  of  higher  cutting  and  return  speeds. 
Since  the  introduction  of  high-speed  steel  there  has  been  a  growing 
demand  for  higher  planer  speeds,  but  the  difficulty  is  due  in  a  con- 
siderable measure  to  the  reciprocating  movement  of  the  heavy  table. 


Fi3.  533 


Designers  are  beginning  to  see  the  necessity  of  providing  some  means 
for  cushioning  this  mass  of  metal,  and  some  efforts  have  been  recently 
made  with  this  in  view. 

Open -side  Planer. — Fig.  504  shows  a  rear  view  of  the  Detrick  &  Har- 
vey open-side  planer.  As  will  be  seen  this  machine  has  but  one  housing 
casting.  The  object  of  this  design  is  to  provide  for  wider  work  than 
would  pass  between  two  castings.  The  overhang  necessitates  a  very 
heavy  cross-rail  and  housing  casting,  and  one  rear  view  of  the  machine 
is  presented  in  order  to  better  show  the  proportions  of  these  parts.  In 
these  machines  the  pulley-shaft  is  parallel  to  the  planer-table,  spiral 
gears  being  used  to  operate  the  latter.  The  tables  are  reversed  "at  a 
ratio  of  from  three  to  four,  to  one,  depending  upon  the  size  of  the 
planer."  In  this  respect  the  open-side  planer  is  about  the  same  as 
other  planers. 

For  work  extending  much  beyond  the  end  of  the  cross-rail  a  supple- 
mental rolling  table  is  furnished  with  the  open-side  planer.  This  sup- 
plemental table  is  shown  in  connection  with  Fig.  505,  which  is  a  front 
view  of  the  planer. 

Extension -heads. — In  the  absence  of  a  planer  of  the  above  descrip- 
tion, wide  work  may  be  planed  by  the  use  of  the  extension-arm  shown 


PLANERS  AND  SHAPERS 


363 


in  Fig.  506.     This  extension  is  fastened  to  the  tool-slide  by  the  same 
bolts   which  ordinarily   hold   thet  tool-block,   the  latter  being  secured 


*    . 


FIG.  504. 

on  the  outer  end  of  the  arm.     This  device  is,  of  course,  not  so  satis- 
factory as  the  open-side  planer. 

Extra  Heads  on  Large  Planers. — Some  of  the  larger  size  planers 
have  two  cross-heads  or  tool-heads  and  take  two  cuts  at  once;  and 
the  largest  planers  have,  in  addition  to  the  above,  one  head  on  each 
of  the  housing  castings,  making  four  heads.  The  planer  shown  in  Fig. 
505  has  three  tool-heads. 


364 


MACHINE-SHOP  TOOLS  AND  METHODS 


Difference  Between  the  Shaper  and  Planer.     Different  Designs  of 

Shapers. — The  shaper  is  a  kind  of  small  planer.  One  essential  differ- 
ence between  the  two  machines  is  that  in  the  typical  planer  the  work 
moves  to  the  tool,  while  in  the  shaper  the  tool  moves  to  the  work. 

Shapers  are  made  in  two  leading  designs  respecting  the  ram  movement, 
namely,  crank-shapers  and  geared  shapers.  In  the  crank-shaper  the  ram 
is  driven  directly  or  indirectly  by  a  crank  movement.  In  the  geared  shaper 
the  ram  is  driven  by  a  gear  meshing  in  a  rack  on  the  under  side  of  the  ram. 

General  Description  of  a  Crank-shaper. — Fig.  507  is  a  perspective 
view  of  a  " Cincinnati"  back-geared  crank-shaper,  and  Figs.  508,  509, 


FIG.  505. 

and  510  are  sectional  views.  Similar  letters  refer  to  similar  parts  in  all 
the  views.  Referring  to  Fig.  507,  A  is  the  box  frame  or  column;  B  the 
ram  sliding  in  guides  on  top  of  A,  and  carrying  the  cutting-tool;  C  the 
graduated  swiveling-plate,  which  may  be  locked  in  any  angle  in  a  ver- 
tical plane;  D  the  tool-slide;  E  the  apron  or  tool-block  on  D;  F  the 


PLANERS  AND  SHAPERS 


365 


FIG.  506. 


FIG.  507. 


366 


MACHINE-SHOP  TOOLS  AND  METHODS 


cross-rail;    G  the  table  and  H  a  vise  detachably  secured  to  the  table. 
The  work  may  be  held  by  bolts  in  T  slots  on  either  of  the  three  faces 


FIG.  508. 

of  the  table,  or  it  may  be  held  in  the  vise.  The  table  may  be  removed 
from  the  saddle  /  and  certain  kinds  of  work  may  be  bolted  to  the  latter. 

Feed-gearing. — The  saddle  is  fed  along  the  rail  F  by  means  of  the 
slotted  crank  J  and  ratchet  and  pawl  device  shown.  The  latter  operates 
a  screw  passing  through  a  threaded  nut  on  the  saddle.  The  cross- 
rail  is  moved  vertically  on  the  planed  face  of  the  column  by  a  crank 
on  the  lower  square-end  shaft. 

Driving-gear. — The  ram  B  is  driven  primarily  by  the  cone  pulley  X 1. 
The  sectional  view,  Fig.  509,  shows  that  this  pulley  is  secured  to  the 
shaft  y.  On  this  same  shaft  is  keyed  a  pinion-clutch  u,  which  by  means 
of  the  lever  z'  (Fig.  508)  may  be  engaged  with  the  clutch-teeth  on  gear  w 
(which  turns  freely  on  y),  or  brought  into  mesh  with  the  gear  v.  In 
the  former  case  the  train  of  gears  w,  x,  and  k  would  be  set  in  motion 
and  the  machine  would  be  running  in  single  gear.  In  the  latter  case 
the  gears  u,  v,  x,  and  k  would  be  caused  to  revolve  and  the  machine  (or 
ram)  would  run  slower,  being  in  back-gear. 


PLANERS  AND  SHAPERS 


367 


The  ram  B  receives  its  motion  from  its  connection  at  g  with  the 
oscillating  beam  or  "link"  i,  and  the  operation  of  this  link  is  as  follows: 
Secured  to  the  gear  k  is  an  adjustable  crank-pin,  I,  shown  in  Figs.  508  and 
510.  This  pin  is  journated  in  a  Octangular  block  m.  When  k  rotates 


X1 


FIG.  509. 


FIG.  510. 


it  carries  m  with  it,  and  as  m  is  a  sliding  fit  in  the  slot  in  the  link,  the 
latter  is  caused  by  m  to  oscillate  through  an  angle  depending  upon  the 
radial  distance  of  the  crank-pin  from  the  axis  of  the  gear  k. 

Quick  Return. — During  the  time  that  the  crank-pin  is  moving  in  the 
upper  part  of  its  circular  path  the  ram  is  moving  forward.  In  the  lower 
portion  of  its  path  the  crank-pin  approaches  closer  to  the  pivot  X  2  of 
the  link,  and  the  motion  of  the  ram  is  reversed  at  a  higher  velocity. 

Stroke  Adjustment. — The  length  of  ram-stroke  is  adjusted  by  moving 
the  crank-pin  I  (Fig.  510)  toward  or  from  the  center  of  the  gear  k,  the 
movement  of  I  being  effected  by  the  screw  n,  gears  o,  p,  and  a  crank- 
handle  at  q'.  The  square  end  of  shaft  q  to  which  the  crank-handle  is 
applied  is  seen  just  above  the  cone  pulley  in  Fig.  507.  The  length- 
wise position  of  the  ram  is  changed  by  moving  the  lever  c  (Fig.  508)  and 
turning  the  hand-wheel  /.  The  connection  of  the  latter  with  gears  e  and 
screw  d  is  clearly  shown.  The  ram  may  be  adjusted  while  the  machine 
is  in  motion. 


368  MACHINE-SHOP  TOOLS  AND  METHODS 

Geared  Shapers. — The  general  construction  of  the  geared  shaper  with 
respect  to  the  framework,  table,  cross-rail,  and  feed  mechanism  is  much 
the  same  as  that  of  the  crank-shaper.  The  quick  return,  however,  is 
generally  effected  by  making  a  difference  in  the  diameters  of  the  driving- 
pulleys.  As  previously  stated,  the  ram  is  driven  by  a  rack  and  gear  move- 
ment. The  driving  mechanism  of  a  geared  shaper  does  not  differ  suffi- 
ciently from  that  of  a  planer  to  justify  a  detailed  description  here. 

The  Traverse  Shaper. — In  the  ordinary  shaper  the  ram  has  only  one 
movement — the  reciprocating  movement — the  work  being  fed  by  the 
intermittent  movement  of  the  table  on  the  cross-rail  at  right  angles  to 
the  ram  movement.  The  traverse  shaper  illustrated  in  Fig.  511  is  so 
called  from  the  fact  that  the  ram,  in  addition  to  its  reciprocating  move- 
ment, is  given  an  intermittent  traverse  or  feeding  motion  at  right  angles 
to  its  reciprocating  motion. 

These  machines  are  made  either  with  two  rams  or  one,  bat  they 
nearly  always  have  two  tables.  As  indicated  above,  the  tables  do  not 
need  any  feed  motion,  but  they  may  be  independently  adjusted  in  ver- 
tical and  Horizontal  directions  on  the  main  frame.  The  driving  mech- 
anism of  this  machine  consists  of  the  pulley  P,  the  gears  operating 
the  crank-gear  G,  and  the  rod  C  connecting  G  with  the  ram.  The 
means  of  changing  the  length  of  stroke  by  moving  the  crank-pin 
toward  or  from  the  center  in  the  slot  in  G  will  be  readily  understood 
from  the  engraving.  The  hidden  end  of  the  connecting-rod  C  is  jour- 
naled  on  a  stud  or  wrist-pin^  which  is  adjustable  in  a  slot  lengthwise  of 
the  ram,  and  it  is  by  this  means  that  the  position  of  the  ram  is  changed. 
The  intermittent  feed  of  the  ram  by  means  of  gears,  screw,  etc.,  is  but 
little  different  from  that  of  the  table  feed  of  the  common  shaper.  These 
machines  are  especially  adapted  for  very  long  work. 

Ram  Movement  on  Geared  Shapers  and  Crank-shapers  Compared.— 
In  the  geared  shaper  the  motion  of  the  ram  is  uniform  as  to  velocity, 
but  not  well  controlled  as  to  length  of  stroke;  that  is  to  say,  when 
adjusted  for  a  given  length  it  may  travel  a  fraction  more  or  a  frac- 
tion less.  This  is  due  to  a  slight  irregularity  in  the  action  of  the 
belts.  In  the  crank-shaper  the  motion  is  not  uniform,  but  the  length  of 
stroke  is  accurately  controlled  by  the  positive  connections.  In  such 
exceptional  cases  as  necessitate  planing  to  a  line,  the  crank-shaper  has 
the  advantage. 

Variable -speed  Shaper-gear. — The  tendency  to  substitute  tooth 
gearing  for  cone  pulleys  has  been  referred  to  elsewhere  in  this  work.  In 
Figs.  512  and  513  illustrate  the  variable-speed  gearing  adapted  to  a 


PLANERS  AND  SHAPERS 


369 


shaper.  Referring  to  Fig.  512,  on  the  shaft  d  is  a  nest  of  gears  which 
serve  the  same  purpose  as  a  cone  pulley.  These  in  connection  with  the 
back-gearing  give  a  wide  range* of  speeds  to  the  ram.  The  shaft  a,  to 


which  the  long  pinion  b  is  keyed,  is  driven  directly  by  the  belt,  or  indirectly 
by  the  back-gears.  These  are  not  shown  in  the  engraving.  The  inner 
end  of  the  shaft  a  is  journaled  in  the  bracket  as  shown.  Journaled  in 


370 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  same  bracket  is  a  short  shaft  to  which  is  keyed  a  frame  e  and  a  large 
spur-gear.     For  each  gear  in  the  cone-of-gears  at   c  an  idler  gear  is 


FIG.  512. 

mounted  on  the  frame  e.  By  a  pinion  meshing  into  the  large  gear 
referred  to  and  the  handle  seen  on  the  outside,  the  frame  e  may  be 
rotated  to  bring  any  one  of  the  six  idler  gears  in  mesh  with  its  mating 
gear  on  the  shaft  d,  and  with  the  long  pinion  6.  Thus  a  number  of 


'American  ,V<ic«n(rt) 


FIG.  513. 

speeds  of  the  ram  are  obtained,  each  depending  on  the  ratio  of  the 
long  gear  b  to  the  one  in  mesh  on  the  shaft  d. 

Swiveling  the  Tocrl-slide  and  the  Tool-apron. — The  principles  of  swivel- 
ing  the  compound  rest  for  turning  bevel-gears,  as  explained  in  Chapter 
XVII,  apply  equally  well  to  the  tool-slide  of  the  planer  or  shaper.  As  in 


PLANERS  AND  SHAPERS 


371 


the  previous  case,  tne  workman  is  very  apt  to  take  the  complement  of 
the  angle  for  the  required  angle,  .both  in  setting  the  tool-slide  and  in 
testing  the  work  with  the  protractor.  If  the  angle  on  the  drawing  is 
given  from  the  vertical,  the  tool-sttde  may  be  swiveled  directly  to  that 
angle;  but  if  an  angle  less  than  90°  be  given  from  the  horizontal,  that 
angle  subtracted  from  90°  will  give  the  angle  at  which  the  tool-slide  is 
to  be  clamped. 

As  indicated,  the  object  of  swiveling  the  tool-slide  is  to  plane  the 
work  at  some  angle  other  than  a  right  angle  with  the  table.  The  object 
of  swiveling  the  tool-apron  is  entirely  different.  The  tool-apron  is 
swiveled  in  downward  cuts  to  relieve  the  friction  of  the  tool  against  the 
work  on  the  return-stroke.  For  this  purpose  the  lower  end  of  the  tool- 
apron  should  be  inclined  toward  the  work. 

A  Tool -lifter. — In  making  an  under  cut  parallel  with  the  surface  of 
the  planer-table,  it  is  necessary  in  the  absence  of  a  special  device  to 


L1 


FIG.  514. 

either  strap  the  tool  down  so  that  it  cannot  lift  at  all  or  to  lift  it  by  hand 
at  the  end  of  each  cut.  The  first  method  is  injurious  to  the  tool;  the 
second  plan,  if  forgotten  for  just  one  stroke,  will  result  in  disaster  to  the 
tool,  or  the  work,  or  both.  Fig.  514  *  shows  a  very  simple  device  which 

*  The  cut   was  made  after  an   illustration  accompanying  an  article  signed 
"Workman,"  published  in  "American  Machinist,"  Nov.  3,  1888,  page  5. 


372  MACHINE-SHOP  TOOLS  AND  METHODS 

may  be  used  for  both  upper  and  under  cutting.  In  this  illustration  T 
is  a  front  view  of  a  tool  shaped  for  under  cutting  a  T  slot,  and  L  is  a 
front  view  of  the  lifter.  The  latter  consists  of  a  thin  plate  of  metal 
having  two  lugs  bent  as  at  L  1  to  receive  pointed  set-screws  which  engage 
with  prick  punch-marks  in  the  sides  of  the  tool.  The  operation  of  the 
device  needs  but  little  explanation.  During  the  cutting-stroke,  the 
lifter,  being  pivoted  at  the  rear  of  the  tool,  strikes  the  work  and  lifts 
above  it  without  disturbing  the  tool.  On  the  return-stroke  the  lifter 
strikes  the  work  and  swings  upward  on  the  pin  to  which  the  tool-apron 
is  pivoted,  carrying  the  tool  with  it.  In  using  such  a  device  the  gibs 
of  the  vertical  tool-slide  must  be  snugly  adjusted,  otherwise  the 
drop  of  the  tool  and  the  tool-apron  just  before  the  beginning  of  the 
cutting-stroke  may  cause  the  tool-slide  to  drop  slightly. 

Adjusting  the  Cross-rail. — In  raising  the  cross-rail,  the  last  movement 
just  before  clamping  the  rail  should  be  upward.  If  the  rail  be  raised 
and  then  lowered  a  slight  amount,  its  parallelism  with  the  table  may  be 
disturbed. 

Planer  and  Shaper  Work. — As  to  the  work  done  on  the  planer  and 
shaper,  it  will  be  understood  that  both  are  designed  mainly  for  plane 
surfaces  as  distinguished  from  round  work  done  on  lathes.  The  short 
stocky  work  can  be  more  conveniently  done  on  the  shaper,  while  the 
planer  is  used  for  larger  work. 

Fig.  515  shows  a  vise  much  used  on  planers  and  shapers.  The 
method  of  clamping  the  work  between  the  jaws  will  be  readily  under- 


FIG.  515. 

stood.    The  vise  swivels  on  its  graduated  base,  thus  providing  for  plan- 
ing work  at  various  angles  with  the  jaws. 

There  is  some  difficulty  in  accurately  clamping  the  work  in  a  vise 
like  that  of  Fig.  515.  There  is  of  necessity  some  freedom  in  the  sliding 
jaw,  and  the  pressure  required  to  hold  the  work  tends  to  slightly  lift 
the  latter.  Many  different  vises  have  been  designed  with  the  object  of 


PLANERS  AND  SHAPERS  373 

overcoming  this  difficulty.  Fig.  516  shows  one  of  these  designs.  The 
illustration  represents  a  piece  of  work  held  by  pins  which  are  in  contact 
with  the  work  at  one  end  and*  with  the  vise  jaws  at  the  other.  When 


FIG.  516. 

the  jaw  is  screwed  up  it  tends  to  force  the  work  down  rather  than 
up.  This  arrangement  admits  of  planing  very  thin  work  without 
blocking  it  up. 

By  light  firm  taps  of  the  hammer,  in  which  the  hammer  is  not  per- 
mitted to  rebound,  the  experienced  workman  can  overcome  the  diffi- 
culty referred  to  in  the  use  of  the  common  vise.  By  pulling  strips  of 
tissue-paper  placed  under  the  ends  of  the  work,  he  is  enabled  to  ascertain 
when  the  work  is  properly  bedded.  If  the  vise- jaws  are  not  square  it 
may  be  necessary  to  use  paper  or  tin  between  the  jaws  and  the  work 
to  square  the  latter, 

Holding  Work  by  Pins  and  Stops. — The  principle  employed  in  con- 
nection with  Fig.  516  is  also  used  in  clamping  work  without  a  vise. 
In  Fig.  517  is  shown  a  piece  of  work  held  to  the  planer-table  in  this 
manner.  The  stops  S  closely  fit  round  holes  drilled  in  the  planer-table, 
and  by  tightening  the  set-screws  in  connection  with  the  pins  P  the 
work  is  forced  down  against  the  table.  These  pins  are  usually  made  of 
3/s-  to  J /2-inch  round  tool  steel,  having  hardened  conical  points  at 
each  end.  The  set-screws  are  countersunk,  the  angle  being  greater 
than  the  points  of  the  pins.  If  the  work  be  inclined  to  tip  on  one  side, 
lowering  the  point  of  contact  between  the  work  and  the  pins  on  that 
side  will  tend  to  bring  it  down. 


374 


MACHINE-SHOP  TOOLS  AND   METHODS 


These  pins  should  not  be  relied  upon  to  take  the  thrust  of  the  cut. 
For  this  purpose  long  and  short  planer  stops  like  S  1  with  or  without 
the  set-screws  are  commonly  used.  These  stops  are  sometimes  made 
with  the  set-screw  holes  parallel  with  the  planer-table,  two  or  three 


FIG.  517. 


holes  being  provided  in  the  longest  stops.  When  thus  made  they  can 
be  used  as  adjustable  stops  to  take  the  thrust  of  the  cut,  or  by  turning 
them  so  as  to  bring  the  set-screw  out  of  the  way  they  may  be  used  with- 
out the  adjustment.  At  A  is  shown  a  device  which  may  be  used  (in 
connection  with  pins)  in  the  T  slots  instead  of  the  round  stops.  These 
may  be  made  about  7/s"  thick  and  about  3"  long  in  the  direction  of 
the  planer  length.  It  is  well  to  have  both  kinds. 

At  B  is  shown  a  small  angle-plate  having  a  tongue  to  fit  in  the  slots 
of  the  table.  In  some  cases  work  may  be  clamped  with  one  edge  against 
the  angle-plate  without  any  pins,  the  pins  on  the  other  edge  of  the  work 
holding  it  down.  In  this  case  the  points  of  contact  between  the  pins 
and  the  work  should  be  raised  so  that  the  points  of  pressure  shall  fall 
approximately  in  a  line  extending  centrally  along  the  base  of  the  work. 

The  V  blocks,  straps,  bolts  and  angle-plates,  shown  in  connection 
with  drill-press  work,  boring-machine  work,  etc.,  may  be  used  in  clamp- 
ing work  on  the  planer.  Special  V  blocks  are  shown  in  Figs.  581  and 


PLANERS  AND  SHAPERS  375 

592,  and  a  very  convenient  strap  is  described  in  connection  with  Fig.  585. 
V  blocks  and  special  fixtures  for  the  planer  should  usually  have  a  tongue 
fitting  the  central  table  slot,  and  the  upper  part  of  such  fixtures  should 
be  planed  while  the  fixture  is  clamped  in  the  slot. 

In  planing  light  work  on  the  planer,  and,  indeed,  most  work  that 
requires  accuracy,  it  is  necessary  to  rough-out  the  work  all  over  before 
taking  the  finishing  cuts.  The  pressure  of  the  straps  or  pins  should  be 
barely  sufficient  to  hold  the  work  when  the  final  cut  is  made,  otherwise 
the  work  may  be  warped.  The  work  should  be  firmly  held  for  the 
roughing  cuts  and  just  before  the  final  cuts  are  taken  the  pressure  of 
the  straps  should  be  relieved. 

Blocking-up  Under  the  Work. — In  planing  a  rough  casting  or  forging, 
even  when  the  base  of  the  latter  is  nominally  flat,  it  is  usually  necessary 
to  block  up  under  the  work  with  tin,  paper,  etc.  Good  judgment  is 
necessary  in  doing  this  to  avoid  warping  or  springing  the  work.  Take, 
for  instance,  a  piece  of  rectangular  plate,  say  12"  wide  by  24"  long. 
In  blocking  up  this  work  two  corners  diagonally  opposite  should  be  taken 
care  of  first.  When  these  are  properly  leveled  up  with  the  " surface 
gage"  (see  Fig.  35),  the  other  two  corners  may  be  blocked  up  in  a  simi- 
lar manner.  If,  however,  the  casting  is  of  such  a  design  as  to  be  appre- 
ciably sprung  by  its  own  weight,  it  may  be  necessary,  in  order  to  balance 
the  weight,  to  put  the  first  blocking  some  distance  from  the  ends.  After 
this  is  done,  the  work  may  be  blocked  at  intermediate  points  from  about 
4  to  16  inches  apart,  depending  upon  the  length  and  shape  of  the 
piece. 

Some  otherwise  good  workmen  use  very  poor  judgment  in  "bed- 
ding" work  on  the  planer.  They  seem  to  think  that  anything  that 
will  fill  up  the  cracks  will  answer.  This  is  a  mistake.  If  the  work 
be  blocked  or  bedded  with  strips  of  tin  which  are  bent  out  of  shape, 
these  will  "give"  under  the  pressure  of  the  straps,  causing  the  work  to 
spring  out  of  shape.  To  avoid  the  same  difficulty  any  fine  lumps  of 
sand  or  scale  left  on  the  casting  by  the  foundryman  should  be  "rasped  " 
off  with  an  old  file.  Small  narrow  strips  of  tin  and  sheet  iron  hammered 
true  and  having  the  ragged  edges  filed  off  should  be  used.  In  addi- 
tion to  these,  the  workman  should  collect  small  blocks  of  cast  iron, 
parallel  blocks  and  jacks.  Common  bolts  with  one  or  two  nuts  on 
the  end  may  be  used  for  jack-screws  in  the  absence  of  a  better  device. 
Adjustable  parallel  blocks  like  those  shown  in  Fig.  518  are  very  useful 
in  blocking  up  finished  work  on  the  planer.  The  cut  was  made  after 
a  design  by  Fred  I.  Getty,  which  was  illustrated  in  "American  Ma- 


376 


MACHINE-SHOP  TOOLS  AND  METHODS 


chinist,"  May  8,  1886,  page  6.     However,  the  author  used  a  slightly 
different  design  previous  to  the  above  date. 

Planer  Tools  and  Work. — The  principles  governing  the  shape  of 
planer-tools  being  in  the  main  the  same  as  those  which  apply  to  lathe- 


I  '  '  i  I  |  I  I  j  I  |  I  I  |  |  I  m  I  |  I  |  | 
50  55 


60 


n  i  I  I  M  |  |  [  |  |  | 


FlG.   518. 

tools,  the  two  classes  of  tools  have  been  treated  in  one  chapter. 
Figs.  300,  301,  302,  and  311  in  that  chapter  indicate  methods  of  doing 
certain  kinds  of  planer  work.  One  principle  which  applies  to  the  use  of 
tools  having  a  broad  bearing  should  be  emphasized,  namely,  that  such 
tools  if  held  on  the  tool-apron  chatter  less  and  work  better  otherwise, 
when  so  made  that  the  spring  of  the  tool  and  freedom  of  the  tool-apron 
pin  cause  the  tool  to  move  from  the  work  rather  than  toward  it.  This 
principle  requires  that  the  tool  have  a  backward  offset,  as  showTn  in 
Fig.  311. 

The  capacity  of  the  planer  for  doing  work  rapidly  is  not  under- 
stood by  the  majority  of  mechanics.  With  a  planer  sufficiently  rigid 
and  tools  properly  constructed,  surprisingly  wide  cuts  may  be  taken. 
Fig.  519,  which  illustrates  an  article  in  the  "  American  Machinist,"  vol. 
27,  page  41,  shows  a  broad-edge  tool  planing  the  flat  surface  between  the 
V's  on  a  lathe-bed.  This  tool  is  held  in  a  special  holder  which  is  gibbed 
to  the  guides  of  the  tool-slide  in  the  same  manner  that  the  tool-slide 
itself  is  gibbed.  To  make  room  on  the  guides  the  tool-slide  is  raised 
to  its  highest  position,  the  holder  being  connected  to  the  regular  tool- 


PLANERS  AND  SHAPERS 


377 


apron  by  a  link  as  shown.     Thus  connected,  the  tool-holder  may  be 
fed  down  with  the  tool-slide  screw. 

Top  and  front  views  of  the  holder  are  shown  respectively  in  Figs. 
520  and  521.     The  broad  tpol  is  heM  by  three  bolts,  and  a  slight  adjust- 


FIG.  519 

ment  is  provided  by  two  set-screws.  Being  independent  of  the  tool- 
apron  pin  and  set  well  back  of  the  latter,  the  tool  does  not  need  to  be 
bent  backward.  As  will  be  seen,  it  is  placed  at  an  angle  of  about  30° 
with  the  cross-rail,  thus  giving  it  a  shearing  cut.  This  arrangement, 
together  with  the  extra  rigidity  secured  by  placing  the  tool  nearer  to 
the  cross-rail,  overcomes  the  tendency  toward  chattering  and  con- 
tributes to  general  smoothness  of  action. 

The  above  tool  was  used  on  cast  iron,  but  steel  is  sometimes  planed 
very  smoothly  by  giving  the  tool  a  shearing  cut.  However,  the  edge 
of  the  tool  is  only  about  1"  wide  and  is  rounded  so  as  to  touch  only 
in  the  middle,  a  fine  feed  being  used. 

Planing  Curved  Work.  —  Although  the  planer  and  shaper  are 
designed  mainly  for  plane  surfaces,  round  work,  irregular  forms,  and 
even  gears  may  be  cut  on  both  machines.  Referring  to  Fig.  522, 
T  represents  the  planer-table  and  C  and  C  1  planer-centers.  These 


378 


MACHINE-SHOP  TOOLS  AND  METHODS 


are  something  like  the  head-  and  tail-stock  of  a  lathe.  The  hanger  B, 
which  obviously  cannot  well  be  turned  in  the  lathe,  is  driven  on  the 
mandrel  M  and  placed  between  centers.  For  each  stroke  of  the  planer, 
B  is,  by  means  of  the  handle  H,  caused  to  move  around  its  axis  a  small 

FIG.  520. 


FIG    521. 

fraction  of  a  revolution.  H  gives  motion  to  the  spindle  in  C  by  means 
of  the  worm-gearing  shown.  When  the  hanger  is  rotated  the  pin  P 
must  be  withdrawn.  This  process  of  feeding  the  hanger  to  the  tool 
is  continued  for  each  successive  stroke  of  the  planer-table  until  the 
work  is-  finished,  v~»* 

This  method  can  be  used  in  the  shaper  also. 

"  The  Concave  Attachment."— The  object  of  the  attachment  shown 


PLANERS  AND  SHAPERS 


379 


in  Fig.  523  is  indicated  by  its  title.     The  movement  of  the  ram  causes 
the  lower  lever  to  swing  in  an  arc.     This  actuates  the  pawl  and  ratchet 


FIG.  522. 

mechanism,  which  by  means  of  the  spur-  and  worm-gearing  shown 
gives  the  circular  movement  to  the  tool.  This  device  cannot  be  used 
on  the  planer. 


FIG.  523 

The  Convex  Attachment. — Referring  to  Fig.  524,  it  will  be  seen  that 
the  table  of  the  shaper  is  removed  and  a  device  having  an  arbor  with 
two  cones  is  bolted  in  its  place.  This  is  a  circular  attachment  for 
round  and  convex  surfaces.  The  work  is  held  on  the  two  cones  just 
the  same  as  in  the  case  of  the  arbor  for  tapering  work  shown  in  Fig.  359. 
This  attachment  has  automatic  feed,  which  is  operated  substantially 
in  the  same  manner  as  the  table.  The  principal  difference  is  that 
the  worm  and  worm-wheel  are  used  in  place  of  the  screw  and  nut. 

Planing  Irregular  Forms. — The  attachments  mentioned  above  are 
designed  more  particularly  for  round  work  or  regular  curves.  The 
former  principle,  as  was  stated  in  the  chapter  on  lathe  work,  may  be 
used  in  machining  either  regular  or  irregular  curves.  In  Figs.  525  *  and 

*  Figs.  25  and  526  were  copied  from  cuts  used  in  connection  with  an  article 
by  "I.'W."  in  "American  Machinist,"  April  21,  1892,  page  6. 


380 


MACHINE-SHOP  TOOLS  AND  METHODS 


526  is  shown  the  end  of  a  round  rod  which  is  widened  and  flattened  at  E, 
the  two  elements  being  joined  by  a  curved  surface.  The  work  in  this 
case  is  to  be  machined  on  both  sides  of  the  flat  end,  and  to  facilitate  the 
operation  the  work  is  held  between  planer-centers.  As  in  the  case  of 


FIG.  524. 

lathe  work,  the  screw  by  which  the  tool  is  fed  to  the  work  is  removed, 
the  movements  of  the  tool  being  controlled  by  the  former  shown.  To 
force  the  tool  to  follow  the  curved  form,  the  bracket  C  is  bolted  to  the 
tool-box,  and  in  the  projecting  arm  of  this  bracket  is  a  bolt  D,  on  the 
lower  end  of  which  is  a  roller,  or  some  equivalent,  in  contact  with  the 
former.  To  adjust  the  tool  for  a  deeper  cut  the  set-screw  holding  the 
bolt  D  is  loosened  and  the  nut  tightened.  The  tool-slide  is  weighted 
down  at  A.  The  weight  at  B  is  designed  to  balance  the  pressure  and 
prevent  the  cramping  of  the  tool-slide  in  its  guide 

The  former  principle  may  be  applied  also  when  the  curved  surface 
lies  crosswise  the  planer.  In  this  case  the  former  may  be  fixed  to  the 
cross-rail  or  to  the  housing. 

It  should  be  understood  that  the  curve  produced  by  the  method 
above  outlined  will  not  be  a  duplicate  of  that  of  the  former.  The  difference 
arises  from  the  difference  in  shape  between  the  point  of  the  tool  and  the 
roller.  This  is  well  understood  by  mechanics  who  have  had  experience 


PLANERS  AND  SHAPERS 


381 


in  laying  out  cams.  For  the  benefit  of  the  inexperienced,  the  following, 
from  an  article  in  the  "  American  Machinist,"  April  21,  1892,  page  2,  by 
Fred  J.  Miller,  is  given.  As  suggested  by  Mr.  Miller  the  form  in  the 


FIG.  525. 


FIG.  526. 


accompanying  illustration  is  of  such  abrupt  curvature  as  would  be 
difficult  of  duplication  on  the  planer,  but  Mr.  Miller  takes  an  extreme 
case  in  order  to  show  the  principle  more  clearly.  He  says:  " Having 


FIG.  527. 

shown  that  a  template  of  the  exact  form  of  the  work  will  not  reproduce 
itself,  the  question  is  how  we  shall  determine  the  form  of  template  to 
produce  a  given  form.  To  do  this  we  have  only  to  lay  out  the  form  of 
the  work,  and  having  decided  the  size  of  the  roller  we  are  to  use,  draw 
another  line  parallel  to  the  first  and  at  a  distance  from  it  equal  to  the 
radius  of  the  roller.  Suppose,  for  instance,  we  wish  to  reproduce  a 


382 


MACHINE-SHOP  TOOLS  AND  METHODS 


form  corresponding  to  that  of  the  template  a,  Fig.  527.    We  draw  a 
line  ab,  Fig.  528,  of  the  desired  form,  and  taking  many  points  on  this 


FIG.  528. 

line  as  centers,  we  strike  arcs  as  shown,  the  radius  of  these  arcs  being 
equal  to  the  radius  of  the  roller  we  are  going  to  use.  A  line  a'b'  drawn 
tangent  to  all  these  arcs  is  the  desired  form  of  template." 

A  number  of  different  methods  of  planing  irregular  forms  are  shown 
in  "  American  Machinist,"  vol.  27,  pages  512  and  544. 

Cutting  Gears  in  Planer  and  Shaper. — Fig.  529  shows  a  method  of 
cutting  teeth  in  gears.  For  this  purpose  the  index-plate  R  has  several 


FIG.  529. 

circles  of  holes  answering  to  various  numbers  of  gear-teeth.  If  we  wish 
to  cut  20  teeth,  the  pin  P  is  adjusted  to  the  circle  of  20  holes.  Having 
tightened  the  cross-head  to  prevent  lateral  movement,  the  tool  is  next 
fed  downward  until  the  first  space  is  cut.  We  now  stop  the  planer, 
pull  the  index-pin  out  and  turn  the  index-plate  (and  gear)  1/2o  revolu- 
tion for  the  next  space,  continuing  the  process  until  the  gear  is  finished. 
Cutting  Rack -teeth. — Fig.  530  illustrates  an  article  by  the  author  in 
"American  Machinist,"  March  31,  1904.  Referring  to  the  figure,  R  is  a 
cross-section  of  the  toothed  ram  belonging  to  the  arbor-press  shown  in 
Fig.  367.  The  ram  was  held  crosswise  on  the  planer-table  by  the  straps 
S,  parallel  block  B  (also  strapped  to  table),  and  pin  P.  The  pin  was 
driven  into  the  ram  to  resist  the  tendency  of  the  latter  to  roll.  Having 
firmly  secured  the  ram,  the  teeth  were  next  roughed  out  with  a  common 


PLANERS  AND  SHAPERS 


383 


square-nose  tool,  the  straps  being  alternately  changed  when  approached 
by  the  tool  in  its  movement  across  the  table.  To  finish  the  teeth  a  B.  &  S. 
four-pitch  rack-cutter  was  bolted  to  a  bar  of  steel,  the  latter  being  held  in 
the  tool-post  as  shown.-  The  sicfe  of  this  bar  was  planed  by  securing  a 
tool  to  the  table  and  feeding  the  bar  to  the  reciprocating  tool. 


h 


I 


FIG.  530. 


America*  JfacAtnim 


The  most  important  part  of  this  apparatus  is  the  disk  D,  by  which  the 
rack-teeth  were  spaced.  This  was  made  for  the  job,  but  has  since  been 
used  hi  cutting  other  racks.  The  periphery  of  the  disk  is  divided  by 
250  lines.  As  the  planer-screw  is  Va"  lead,  each  division  on  the  disk 
represents  .001",  and  .0005"  can  be  measured  by  estimation.  In  spacing 
the  teeth,  the  tool  had  to  be  moved  .7854"  (practically  .7855").  The 
stopping-point  on  the  disk  for  each  spacing  was  indicated  by  making  a  light 
line,  in  a  "touch"  of  red  lead,  corresponding  to  the  zero-line  on  the 
cross-rail.  Thus  .7855"  was  measured  from  a  new  starting-point  for 
each  tooth. 

With  a  more  expensive  fixture  the  cutter  could  of  course  be  made  to 
revolve,  and  thus  mill  the  work. 

One  is  justified  in  using  the  planer  or  shaper  in  cutting  gears  only 
when  a  milling-machine  or  gear-cutter  is  not  available. 


384 


MACHINE-SHOP  TOOLS  AND  METHODS 


Grinding  Attachments  for  Planer  and  Shaper. — Fig.  531  shows  an 
attachment  for  the  planer  which  should  prove  of  great  value  in  many 
shops  where  a  regular  surface-grinder  is  not  available.  The  bracket 
carrying  the  emery-wheel  arbor  is  shown  at  B.  It  is  held  on  the  tool- 
block  or  tool-slide  by  four  bolts,  and  the  emery-wheel  arbor  is  driven 
from  an  auxilhary  countershaft  as  shown.  The  latter  is  driven  from 


FIG.  531. 

the  mam  countershaft  of  the  machine.  To  provide  for  the  crosswise  feed 
of  the  emery-wheel,  a  long  pulley  or  drum  is  generally  used  on  the  auxil- 
iary countershaft  of  such  attachments  when  work  of  considerable  width 
is  to  be  ground.  The  small  flanged  pulley  shown  keeps  the  lower  part 
of  the  belt  in  position. 

The  attachment  shown  in  Fig.  531*  was  designed  to  be  used  either 
in  the  planer  or  lathe.  Fig.  532  shows  the  same  emery-wheel  and  bracket 
secured  to  the  compound  rest  of  an  engine-lathe.  The  work  is  that  of 
grinding  a  narrow-face  wheel.  In  such  work  the  drum  on  the  counter- 
shaft is  unnecessary. 


*  Figs.  531  and  532  are  from  cuts  accompanying  an  article  by  C.  H.  Alexander 
in  "American  Machinist,"  vol.  26,  page  1121. 


PLANERS  AND  SHAPERS 


385 


In  Fig.  533  is  shown  a  surface-grinding  attachment  *  for  the  shaper, 
and  it  is  also  held  on  the  tool-apron.  On  account  of  the  reciprocating 
motion  of  the  ram,  it  is  necessary  to  use  a  tightener  as  shown  at  D. 
This  tightener  automatically  maintains  the  tension  on  the  belt.  Unless 
the  attachment  is  used  on  the  traverse  shaper,  a  narrow-faced  pulley  may 


American  Machinist 


FIG.  532. 


be  used  on  the  auxiliary  countershaft  instead  of  the  long  drum  referred 
to  in  connection  with  Fig.  531. 

Care  of  Planer-table.  —  The  planer-table  is  curved  or  peened  by 
driving  down  the  stops  too  hard,  by  letting  heavy  work  fall  on  it,  by 
hammer-blows,  etc.  Not  only  is  the  table  curved  by  such  usage,  but 
lumps  are  raised  on  it  which  prevent  planed  work  from  resting  solidly. 
It  is  difficult  to  get  the  beginner  to  see  that  the  smallest  bruise  or  scratch 
or  speck  of  grit  may  cause  the  last-mentioned  difficulty.  Before  clamp- 
ing such  work  it  is  often  advantageous  to  sweep  an  old  smooth  file  over 
the  table  surface  in  such  a  manner  as  to  scrape  off  fine  lumps  and  show 

*  Fig.  533  is  taken  from  a  cut  which  accompanied  an  article  entitled  "The 
Shaper  as  a  Surface  Grinder,"  by  S.  Bliss,  in  "American  Machinist,"  vol.  27,  page 
595. 


386 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  533. 


PLANERS  AND   SHAPERS 


387 


up  the  large  ones.     After  using  the  brush,  fine  grit  may  be  best  wiped 
off  with  the  hand. 

Testing  the  Bed. — The  planer-table  should   be  planed  when  neces- 
sary.     The  bed  also- may  occasionally  need  attention.     A  method  of 


&       & 

A 

-T—  -  "--  

1                         x 

j 

FIG.  534. 

testing  the  V's  by  using  three  rollers  equal  distances  apart  in  each  V, 
one  straight-edge  or  parallel  block  crosswise  on  each  pair  of  rollers,  and 
a  long  straight-edge  applied  diagonally,  is  illustrated  and  described  by 
"Jarno"  in  the  "  American  Machinist,"  August  11,  1888.  See  Fig. 
534  for  the  illustration. 


CHAPTER  XXIV 

SLOTTING-MACHINES   AND   THE   WORK  TO   WHICH   THEY  ARE 

ADAPTED 

General  Description  of  the  Slotting-machine. — The  slotting-machine 
is  similar  in  principle  to  the  shaper.  Its  ram,  however,  moves  at  right 
angles  to  the  table,  while  in  the  shaper  the  ram  moves  parallel  with  the 
table.  Referring  to  Fig.  535,  B  is  the  bed  cast  integral  with  the  upper 
column  C',  T  the  table;  R  the  ram;  P  the  driving-pulley;  G  the  driving- 
gear;  C  1  the  slotted  crank  connecting  with  R  by  the  connecting-rod  R  1 ; 
F  and  F  1  the  table-feed  gears ;  C  3  a  cam  on  G  for  operating  the  feed- 
gearing;  and  W  the  counterbalance  for  R. 

Table  and  Ram  Movement. — The  table  has  two  movements  at  right 
angles  in  a  horizontal  plane,  and  also  turns  about  its  axis.  These  are 
all  automatic  and  intermittent  movements  effected  by  the  feed  mechanism 
C  3,  F,  and  F  1.  The  table  may  also  be  moved  in  all  the  directions  by 
hand  by  means  of  cranks  on  the  several  table-shafts.  The  ram  movement 
may  be  increased  or  diminished  for  different  thicknesses  of  work  by 
the  slotted  crank.  The  cutting-tool  is  secured  to  the  lower  end  of  the 
ram.  The  operation  of  the  ram  by  means  of  the  driving-pulley  P,  gear 
G,  etc.,  will  be  understood  without  further  explanation. 

Character  of  Work  Done  on  the  Slotting-machine. — In  machining  a 
piece  of  work  which  is  required  to  have  its  sides  at  right  angles,  the 
work  is  bolted  to  the  table,  and  by  means  of  the  two  right-angular 
movements  of  the  table  the  four  sides  of  the  work  are  finished  with 
but  one  adjustment  of  the  work  on  the  table.  If  the  bolts  which  hold 
the  work  on  the  ends,  for  instance,  are  in  the  way  when  machining 
the  ends,  other  bolts  are  placed  on  the  two  finished  sides  before  removing 
the  bolts  on  the  ends.  More  adjustments  would  be  required  if  the  same 
piece  of  work  were  machined  in  the  shaper  or  planer,  and  an  offset-tool 
would  be  needed  for  the  interior  of  a  rectangular  shape. 

Much  of  the  short  stocky  work  done  on  the  shaper  could  be  done 
on  the  slotter,  but  the  slotter  is  specially  adapted  to  cutting  various 
shaped  slots,  to  finishing  the  interior  and  exterior  of  curved  surfaces 

38S 


SLOTTING-MACHINES 


389 


etc.  Among  the  details  which  can  be  machined  advantageously  on 
the  slotter  may  be  mentioned  the  fork-end  connections  for  the  reversing 
gear  of  a  steam-engine,  the  engine  connecting-rod  straps,  the  half  boxes 
for  locomotive  driving*axles,  ai$l  many  kinds  of  die  work.  The  slotting  - 
machine  was  formerly  used  to  a  great  extent  in  cutting  key-seats  in  pul- 


FIG.  535. 

leys,  gears,  etc.      For  this  purpose  it  has  been  superseded  in  a  measure 
by  special  key-seating  machines. 

Portable  Slotting-machines. — In  Fig.  536  we  show  a  portable  slot- 
ting-machine.  This  slotter  is  used  on  a  large  base-plate  for  very  heavy 
work  in  which  it  is  more  convenient  to  move  the  slotter  than  the  work. 
The  vertical  movement  of  the  tool-head  is  effected  by  pulleys,  tooth-gear- 


390 


MACHINE-SHOP  TOOLS  AND  METHODS 


ing  and  a  screw,  but  the  machines  are  also  made  with  a  rack  and  pinion 
movement.     This  machine  has  a  limited  traverse  on  its  sub-base,  and 


FIG.  536 

the  tool-block  has  a  movement  in  the  same  direction  on  the  cross-rail. 
It  has  the  usual  automatic  and  hand  feeds. 

The  construction  of  the  machine  is  such  that  it  is  not  well  adapted 


SLOTTING-MACHINES  39 1 

to  machining  slots  and   interior   surfaces.      Indeed,  the  machine  couid 
with  propriety  be  called  a  vertical  planer. 

Slotting-machine  Tools. — The  tool  used  in  machining  narrow  slots, 
etc.,  cuts  on  its  end  and  is  forged  #n  the  end  of  a  bar  of  steel  in  a  similar 


FIG.  537. 


manner  to  a  common  planer-tool.  The  cutting  angle  and  clearance  of 
these  and  all  other  slotting-tools  should  be  about  the  same  as  those  of 
planer-tools,  excepting  that  the  direction  of  these  angles  should  be 
determined  with  respect  to  a  vertical  plane  rather  than  a  horizontal. 


FIG.  538. 

Fig.  537  shows  the  front  and  side  views  of  a  slotter-tool  such  as  has  been 
mentioned.  The  tool  must,  of  course,  be  forged  down  small  enough 
to  enter  the  slot,  and  in  very  narrow  slots  the  tool  is  sometimes  made 
to  cut  on  both  the  front  and  rear  side,  one  cut  serving  to  brace  the  other. 
In  Fig.  538  is  shown  a  square-end  finishing-tool  which  is  sometimes 
used  as  last  described.  Having  taken  the  finishing  cut  on  both  sides 
of  the  slot  the  ends  of  the  slot  are  finished  separately  with  the  same 
tools.  When  the  slots  are  so  narrow  as  to  require  the  tools  to  be  used 
in  this  manner  the  work  could  usually  be  done  more  advantageously 
in  the  milling-machine.  Some  mechanics  make  slotter-tools  for  fillets 
of  circular  cross-section  at  the  cutting-end.  The  shapes  of  the  cutting- 
edges  for  the  roughing-tools  are  determined  on  the  same  general  prin- 
ciples which  apply  to  lathe-  and  planer-tools. 

In  Figs.  539  and  540  is  shown  a  rotary  tool-holder  which  we  shall 
presently  describe.  The  lower  part  of  this  tool,  which  is  shown  broken 
from  the  upper  part,  represents  the  slotter-tool  commonly  used  for 
exterior  slotting,  and  also  for  interior  when  the  opening  is  large  enough 
to  admit  such  a  tool.  The  tool  T  is  held  by  two  set-screws  in  a  block 


392 


MACHINE-SHOP  TOOLS  AND  METHODS 


which  is  pivoted  to  the  bar  at  P.     The  spring  S  tends  to  hold  the  block 
in  proper  relation  with  the  bar,  but  on  the   return-stroke  this  spring 


FIG.  539. 


American  Michinvtt 

FIG.  540. 


permits  the  tool  to  rock  slightly  on  the  pivot  P,  and  thus  relieve  the 
wear  that  would  otherwise  occur.  If  the  tool  be  secured  directly  to 
the  bar,  as  it  sometimes  is,  there  must  be  considerable  pressure  and 
consequent  wear  during  the  return-stroke. 


SLOTTING-MACHINES 


393 


The  slotting-tool  shown  in  Fig.  541  is  somewhat  similar  to  the  lower 
end  of  the   tool   just   described,.    The  cutting 
part  of  the  tool,  however,  is  helol  in  the  block 
at  an  angle,  giving  it  the  proper  rake  for  free 
cutting. 

A  Rotating  Tool -holder.  —  Some  slotting- 
machines  are  made  without  provision  for 
rotating  the  table.  In  such  a  machine  the  tool- 
holder  shown  in  Figs.  539  and  540  could  be 
used  for  curved  surfaces  of  small  radii.  Refer- 
ring to  the  illustrations,  the  boxes  A  and  B 
are  held  to  the  slotter-head  or  ram  by  four 
studs  as  shown.  The  upper  part  of  the  bar 
is  turned  to  fit  the  boxes  and  also  to  fit  the 
worm-wheel  C.  The  bar  is  rotated  by  the 
hand-wheel  D,  which  operates  the  worm  E 
meshing  with  C. 

This  tool,  however,  was  primarily  designed 
for  finishing  fillets  and  other  curved  surfaces 
on  large  framework,  which  cannot  be  rotated 
on  an  ordinary  slotting-machine.  It  is  fully 
described  by  T.  B.  Burnite  in  "  American 
Machinist/'  vol.  27,  page  125.  FIG.  541. 


CHAPTER  XXV 
KEY-SEATING  MACHINES  AND  KEYS 

Key-seats  and  Key-fitting. — Before  describing  the  key-seating 
machine  it  will  be  necessary  for  the  benefit  of  the  younger  student  to 
explain  what  a  key  is.  In  Figs.  542  and  543,  which  show  a  pulley 


1    - 


FIG.  542. 


FIG.  543. 


keyed  to  a  shaft,  K  is  the  key.     The   rectangular   grooves  cut   into 
the  pulley  and  shaft  are  called  key-seats  or  key  ways. 

In  this  connection  it  may  be  well  to  consider  the  method  of  fitting 
keys.  Some  machinists  think  a  key  should  fit  best  at  top  and  bottom 
(T  and  B) ;  others  prefer  to  have  it  fit  best  on  the  sides,  as  at  S.  In 
important  cases  the  key  should  fit  well  on  both  sides,  and  at  top  and 
bottom.  Sometimes  set-screws  are  placed  in  the  hub  of  the  pulley 
so  as  to  press  on  the  top  of  the  key;  this  obviates  the  necessity  of  close- 
fitting  at  this  point.  A  key  should  not  be  filed  so  as  to  have  a  tight 
bearing  at  top  and  bottom  on  one  end  and  miss  on  the  other  end.  Such 
fitting  is  likely  to  force  the  pulley  slightly  out  of  square  with  the  shaft. 
Keys  which  are  to  fit  at  the  top  and  bottom  are  usually  tapered  on  the 

394 


KEY-SEATING  MACHINES  AND  KEYS 


395 


top  from  1/8  to  3/ie  inch  per  foot.      They  are   never   tapered   on  the 
sides,  and  when  held  by  set-screws  are  not  tapered  on  top. 

In  shops  where  very  little  key-seating  is  required  the  work  is  some- 
times done  with  the  chisel  and  file?  but  where  a  great  deal  of  key-seating 


FIG.  544. 

is  required  it  pays  to  purchase  a  key-seating  machine.  Key-seats  in 
the  shaft  may  be  cut  on  the  milling-machine,  planer,  or  shaper. 

There  has  recently  been  introduced  a  system  of  keys  of  the  shape 
of  a  sector  of  a  circle,  the  top  of  the  key  being  of  exactly  the  same  shape 
as  those  shown  in  the  illustration.  The  key-seats  in  the  shaft  for  such 
keys  cannot  be  planed,  but  must  be  sunk  in  by  a  revolving  cutter. 
The  key-seats  in  the  pulley  may  be  made  by  the  ordinary  process. 

Key-seating  Machines. — Fig.  544  shows  a  key-seating  machine  of 
modern  type.  In  accordance  with  the  most  advanced  ideas  in  machine- 
tool  design  the  column  B  is  of  hollow  or  box  form.  Working  in  guides 


396  MACHINE-SHOP  TOOLS  AND  METHODS 

on  top  of  this  column  is  the  table  T  to  which  the  work  is  fastened.  The 
tight  pulley  P  (there  is  also  a  loose  pulley  not  shown)  is  on  the  same 
shaft  with  a  pinion  (not  shown)  which  operates  the  gear  G.  Keyed 
to  the  same  shaft  as  G  is  a  crank  C  1  which,  by  means  of  the  connecting- 
rod  C  2,  operates  the  cross-head  C.  The  cutter-bar  or  ram  R  is  secured 
to  the  cross-head  by  a  kind  of  ratchet-cam  which  is  operated  by  the 
lever  L.  T  1  is  the  cutting-tool  held  by  a  set-screw  S.  To  support 
the  bar  against  the  pressure  of  the  cutting,  brace  B  1  is  provided.  This 
is  so  constructed  that  it  may  be  adjusted  vertically  and  horizontally 
by  the  levers  L  1  and  L  2,  and  may  be  swung  around  on  the  post  P  1 
when  work  is  to  be  removed. 

In  cutting  a  key-seat,  the  cutter  is  fed  to  the  work  by  the  hand- 
wheel  W ;  by  the  same  hand-wheel  the  cut  is  relieved  on  the  return 
stroke.  The  knob  K,  which  has  micrometer  adjustment,  regulates  the 
depth  of  the  cut;  and  by  means  of  this  micrometer  adjustment,  any 
number  of  key-seats  may  be  cut  to  the  same  depth.  Key-seats  are  often 
made  tapering,  and  for  this  purpose  the  table  is  tilted  by  the  thumb- 
screw V. 

The  machine  above  described  is  one  of  the  smallest  and  simplest 

made,  but  it  shows  the  principle  better  than  the  more  elaborate  designs. 

Key-seating  Attachments. — Various  small  key-seating  devices  have 

been  designed  for  use  in  connection  with  the  arbor-press,  with  the  planer, 

and  with  drilling-machines.  In  Fig.  545  is 
shown  a  key-seating  attachment  for  the 
latter  machine.  The  shank  at  the  upper 
end  is  driven  by  the  ordinary  drill-chuck, 
or  when  made  to  the  Morse  taper  it  is 
driven  in  the  socket  of  the  drill-spindle.  On 
the  end  of  the  same  shaft  of  which  this  shank 
is  a  part  are  a  number  of  pins  which  serve 
as  gear-teeth,  and  which  revolve  the  cutter 
F  shown  at  the  bottom  of  the  device  by  en- 

gagement with  its  teeth.     The  tool  is  guided 

by  one  of  the  bushings  shown,  these  being  made  to  fit  different  sizes 
of  holes,  and  it  is  fed  in  the  same  manner  as  a  drill.  For  taper  keys 
the  hole  in  the  bushing  is  made  at  an  angle  with  the  outside.  While 
the  inner  shaft  and  cutter  revolve,  the  outer  shell  is  prevented  from 
turning  by  the  horizontal  lever  at  the  top. 

For  large  fly-wheels,  large  gears,  etc.,  portable  key-seating  machines 
driven  by  power  are  sometimes  used. 


CHAPTER  XXVI 
MILLING-MACHINES  AND  MILLING-MACHINE  WORK 

General  Description. — The  milling-machine  probably  derives  its 
name  from  the  fact  that  the  operation  of  the  milling-cutter  is  somewhat 
suggestive  of  the  old  millstone  processes.  Fig.  546  shows  a  Brown  & 
Sharpe  Universal  milling-machine.  The  frame  A  is  of  the  box  form 
common  to  machines  of  this  class.  Within  the  hollow  frame  are  shelves 
for  the  smaller  accessories  belonging  to  the  machine,  there  being  a  door 
on  the  side  opposite  to  that  shown  in  the  engraving.  The  head-stock  B 
is  cast  integral  with  the  frame.  Journaled  in  the  head-stock  is  the  spindle, 
the  end  of  which  is  shown  at  C.  The  spindle  of  this  machine  is  not  driven 
by  a  cone  pulley,  but  by  a  system  of  gearing  which  we  shall  presently 
describe. 

The  bracket-shaped  casting  D  is  called  the  knee.  It  is  movable  ver- 
tically and  guided  by  planed  surfaces  on  A.  This  movement  is  effected 
by  the  hand-wheel  E,  which,  by  means  of  bevel-gearing,  operates  the 
telescopic  screw  F.  The  construction  of  the  latter  is  such  that  no  hole 
is  required  in  the  floor  to  receive  the  screw  when  the  knee  is  in  its  lowest 
position.  Supported  on  top  of  the  knee  are  three  members,  of  which  G 
is  called  the  clamp-bed,  H  the  saddle,  and  7  the  table.  G  can  be  moved 
on  Dj  parallel  with  the  spindle  C,  by  the  hand-wheel  /.  This  hand-wheel 
operates  a  screw  working  in  a  nut  secured  to  G.  The  table  I  slides  in 
the  saddle  H,  for  most  purposes  at  rigth  angles  to  the  spindle;  but 
inasmuch  as  H  may  be  swiveled  on  its  graduated  base,  7  may  be  fed 
at  various  angles  with  the  spindle.  The  dividing  head  K  (otherwise 
called  the  spiral  head)  and  the  foot-stock  L  are  bolted  to  the  lathe. 

The  long  shaft  M,  together  with  its  pendent  arm  N,  is  called  the 
overhanging  arm.  The  smaller  cutters  are  carried  on  an  arbor  which  has 
a  tapered  shank  to  engage  with  the  tapered  hole  in  the  spindle,  and  the 
object  of  the  overhanging  arm  is  to  support  the  outer  end  of  the  arbor. 
When  extra-heavy  cutting  is  being  done,  the  arm  itself  is  tied  to  the  clamp- 
bed  by  the  slotted  links  0,  which  are  called  harness,  or  braces.  The  work 


398 


MACHINE-SHOP  TOOLS  AND  METHODS 


is  secured  either  directly  or  indirectly  to  the  table,  and  is  fed  to  the 
revolving  cutter  by  hand  or  by  power. 


FIG.  546. 


The  Driving-gear. — Fig.  547  is  a  sectional  view  showing  the  driving- 
gear,  and  Fig.  548  is  an  end  view  showing  the  gears  in  dotted  lines.    The 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK  399 


400 


MACHINE-SHOP  TOOLS  AND  METHODS 


first  gear  in  the  system  is  a  long  pinion  b.  This  runs  at  a  constant  speed, 
being  driven  by  the  pulley  a.  Meshing  with  b  is  an  intermediate  c 
(Fig.  548)  which  by  levers  h  and  i  may  be  brought  into  mesh  with  d,  e,  f, 
or  g  (Fig.  547),  giving  four  different  speeds  to  the  shaft  bearing  these 
four  gears.  By  means  of  the  lever  k  either  j  or  Z  may  be  brought  into 
mesh  with  one  of  the  four  gears,  thus  multiplying  the  number  of  speeds 
by  two  and  giving  eight  speeds.  The  levers  k,  h,  and  i  are  the  upper, 
middle,  and  lower  levers  shown  at  the  left  of  the  flanged  pulley  in  Fig. 
546. 

Back -gearing. — The  design  of  the  back-gearing  is  similar  in  principle 
to  that  ordinarily  used,  but  the  details  are  quite  different.     The  gears 


Jmerieun  MachiniH 


549. 


/  and  -•£  of  Fig.  547  are  keyed  to  the  quill  m,  upon  the  left  end  of  which 
is  a  pinion  answering  to  the  pinion  commonly  secured  in  the  end  of  a 
cone  pulley.  Integral  with  m  at  the  right  hand  is  a  flange  to  which 
the  usual  large  gear  of  the  main  spindle  is  locked  when  the  machine 
is  in  single  gear.  The  locking-pins  are  seen  at  d  and  e  (Fig.  549).  When 
by  means  of  the  lever  /,  the  back  gears  are  brought  into  mesh,  a  cam  at 
a  on  the  back-gear  shaft  moves,  through  the  lever  b,  a  collar  c,  thus 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


401 


withdrawing  the  locking-pins.  When  the  back-gears  are  disengaged, 
small  springs  pressing  against  the.  locking-pins  d  and  e  are  compressed , 
causing  these  pins  to  enter  the*  sockets  in  the  flange  during  the  first 
revolution  of  the  spindle.  Thus^  the  locking-pins  are  automatically 
engaged  or  disengaged  by  the  back-gear  lever. 

By  the  back-gears  the  number  of  speeds  is  again  multiplied  by  twor 
giving  the  machine  sixteen  spindle  speeds. 

Feed-gearing. — Referring  again  to  Fig.  546,  just  below  and  to  the 


i— I    j    ;  ^ 


^J 


American  Machinitt 


FIG.  550. 


left  of  the  driving-pulley  is  seen  the  feed-box  and  gears,  a  sectional  view 
of  which  is  shown  in  Fig.  550.     The  sprocket  a  is  driven  from  the  pulley- 


402 


MACHINE-SHOP  TOOLS  AND  METHODS 


shaft  through  a  "pitch  chain."  On  the  same  shaft  and  driven  by  a  is 
the  long  pinion  6.  This  pinion,  through  a  shifting  intermediate  gear 
(not  shown),  drives  the  cone  of  gears  d,  e,  f,  g,  h,  i,  two  of  which  alternately 
engage  with  the  shifting  gears  k  and  m  and  drive  the  universal- joint  shaft. 
Thus  ten  different  feeds  are  given,  the  mechanism  being  similar  to  the 
main  driving-gear  with  the  back-gears  omitted. 

Motion  is  communicated  from  the  feed-gearing  to  the  work-table  by 
means  of  mechanism  consisting  principally  of  the  telescopic  shaft  shown 


FIG.  551. 

inclined  toward  the  feed-box  in  Fig.  546,  suitable  gearing,  and  a  screw. 
The  latter  is  shown  in  connection  with  the  saddle  in  Fig.  551. 

Plain  Milling-machine. — In  one  of  its  principal  forms  the  plain 
miller  is  in  general  similar  to  the  machine  just  described.  The  main 
difference  is  that  the  plain  miller  has  no  clamp-bed,  the  table  being  guided 
in  ways  in  the  saddle,  which  is  clamped  directly  to  the  knee.  The 
table  of  the  plain  miller,  therefore,  cannot  be  fed  at  any  other  angle 
than  a  right-angle  with  the  main  spindle.  Fig.  552  shows  a  plain  miller 
designed  in  1897,  in  connection  with  a  class  in  machine  design,  of  which 
the  author  was  instructor.  A  knowledge  of  the  friction  mechanism  em- 
ployed in  this  machine  may  be  of  some  value  to  the  student.  The  friction- 
disk  shown  at  D,  the  driving-face  of  which  is  covered  with  leather,  was 
used  to  a  greater  extent  in  machine-tool  construction  when  this  machine 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


403 


was  designed  than  it  is  at  present.  This  disk  is  driven  by  the  gears  G. 
The  small  cast-iron  pulley  which  is  shown  near  the  middle  of  D,  and 
which  is  driven  by  the  latter,  gives  motion  to  a  train  of  gears  some  of 
which  are  seen  inside  the  knee.  "The  last  of  these  gears,  a  miter,  by 
meshing  with  two  miter-gears  on  the  table-feed  screw,  gives  the  table 
a  forward  or  reverse  traverse,  depending  upon  which  gear  is  in  engage- 
ment with  the  shifting  clutch.  This  reversing  mechanism  is  similar  in 
principle  to  that  shown  at  g,  h,  i,  j,  in  Fig.  221.  In  some  milling- 
machines  the  table  is  driven  by  pinion  and  rack. 

The  small  friction-pulley  runs  in  a  sleeve  which  has  rack-teeth  cut 
on  one  side.     A  pinion  meshing  with  this  rack  is  rotated  by  the  hand- 


FIG.  552. 

wheel  H ,  and  thus  the  pulley  is  moved  from  the  center,  or  zero  position 
of  the  disk,  to  the  periphery,  or  position  of  maximum  feed.  This  move- 
ment may  be  effected  while  the  machine  is  in  motion.  The  excessive 
thrust  on  the  bearings,  which  is  one  objection  to  the  friction-feed,  is 


404  MACHINE-SHOP  TOOLS  AND  METHODS 

largely  overcome  in  this  machine  by  the  use  of'  ball  bearings,  and  the 
mechanism  works  quite  satisfactorily. 

In  addition  to  the  socket  for  taper-shank  arbors  the  spindle  in  this 
machine  is  threaded  to  receive  large  facing  cutter-heads  like  that  shown 
in  the  lower  part  of  the  cut.  In  this  respect  the  spindle  of  the  machine 
in  Fig.  546  is  similarly  designed. 

"Planer-type"  Milling-machine. — As  indicated  by  its  title,  the 
machine  shown  in  Fig.  553  is  constructed  on  the  same  general  plan  as 


FIG.  553 

a  planer.  The  table  affords  ample  area  for  clamping  large  heavy  work, 
and  the  arbor,  which  is  adjustable  vertically  on  the  uprights,  is  firmly 
supported  at  both  ends. 

In  Fig.  554  is  illustrated  an  open-side  milling-machine,  which  serves 
the  same  purpose  in  miller  work  as  the  open-side  planer  serves  in  planer 
work.  Starting  with  the  cone  pulley  seen  projecting  just  above  the 
table,  it  is  easy  to  follow  the  driving  mechanism  through  the  train  of 
gears  to  the  vertical  spindle.  The  feed  of  the  spindle  along  the  cross- 
rail  is  effected  by  two  pairs  of  cone  pulleys,  the  first  being  shown  to  the 
right  of  the  spindle  and  the  second  pair  near  the  overhanging  end  of 
the  cross-rail.  At  the  front  end  of  the  machine  are  seen  two  cone  pulleys 
which,  through  the  worm-gearing  shown  on  the  outside,  and  other 
mechanism  on  the  inside  of  the  frame,  give  the  lengthwise  feed  of  the 
table. 

Planer-type  milling-machines  are  sometimes  made  with  as  many 
as  four  spindles,  two  of  these  being  horizontal  spindles  supported  on 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


405 


the  uprights  or  housing  castings,  and  the  other  two  vertical  spindles 
which  are  journaled  in  a  cross-head  sliding  on  a  cross-rail  as  in  Fig.  554. 


\ 


FIG.  554. 

Vertical  Miller. — The  essential  difference  between  the  vertical  milling- 
macmTTe  aUcPthe  horizontal  miller  is,  of  course,  the  vertical  spindle  of 
the  former.  The  miller  shown  in  Fig.  555  is  driven  from  a  counter- 
shaft having  a  cone  pulley,  etc.  The  cone  pulley  of  the  machine,  how- 
ever, is  not  placed  on  the  main  spindle,  but  on  a  short  shaft  at  P.  On 
this  same  shaft  is  another  pulley  P  1,  from  which  the  power  is  con- 


406 


MACHINE-SHOP  TOOLS  AND   METHODS 


veyed  by  a  belt  running  over  the  idler-pulleys  P  2  to  the  spindle-pulley 
at  P3. 

The  construction  of  the  knee  and  the  table,  and  the  mechanism  for 
operating  these  parts,  do   not   necessarily  differ   in   the  vertical  miller 


FIG.  555. 

from  the  same  parts  in  the  horizontal  miller.  The  rotary  table  shown 
in  Fig.  555  is  not  an  essential  part  of  this  machine.  It  is  detachably 
connected  to  the  main  table,  and  with  suitable  feed  connections  could 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          407 

be  used  on  milling-machines  of  different  construction.  It  is,  however,, 
a  very  desirable  attachment  for  the  vertical  miller.  In  addition  to 
the  vertical  adjustment  of  the  knee,  the  machine  shown  in  the  engrav- 
ing is  provided  with  a  slight  adjustment  for  the  spindle-head.  The 
means  of  feeding  the  head  (and  with  it  the  spindle)  is  a  large  hand- 
wheel  shown  on  the  upper  part  of  the  frame. 

There  are  many  designs  and  modifications  in  milling-machines,, 
including  hand-millers,  but  the  foregoing  represent  some  of  the  leading 
types. 

Milling-machine  and  Planer  Compared. — In  the  milling-machine 
the  cutter  is  connected  to  and  revolves  with  the  spindle.  This  rotary 
motion  makes  the  cutting  practically  continuous,  while  the  planer-tool 
(as  planers  are  commonly  constructed)  cuts  only  during  the  forward 
stroke  of  the  table.  Again,  in  the  planer  a  single-edge  tool  is  generally 
used,  which  tool  dulls  quickly.  A  multiple-edge  tool  being  used  in  the 
miller,  the  work  of  each  edge  is  greatly  lessened.  The  tool,  therefore,, 
holds  its  edge  almost  indefinitely  and  produces  work  more  uniform 
in  shape.  This  is  of  great  importance  in  connection  with  the  inter- 
changeable system  of  manufacturing,  especially  when  curved  shapes 
are  involved.  From  the  above  considerations  it  will  be  apparent  that^-^ 
the  milling-machine  should  be  a  more  economical  tool  than  the  planer. 
Nevertheless,  the  improvements  in  the  planer  in  the  direction  of  making 
the  return-stroke  quicker,  and  the  introduction  of  multiple-edge  tools- 
in  some  cases,  together  with  the  use  of  two  or  more  cross-heads  on  the 
larger  machines,  will  still  enable  this  machine  to  hold  its  ground  in 
competition  with  the  miller  for  many  kinds  of  work.  For  gear-cutting  r^ 
the  miller  is,  of  course,  much  superior  to  the  planer. 

MILLING-MACHINE    CUTTERS,    WORK,    AND    ATTACHMENTS 

In  Figs.  556  to  576  inclusive  are  shown  various  milling-cutters 
the  names  of  which  are  given  in  connection  with  the  cutters.  The 
methods  of  using  some  of  these  cutters  will  be  indicated  in  succeed- 
ing paragraphs. 

Figs.  577  to  584  show  a  number  of  operations  performed  on  a 
machine  made  by  the  Cincinnati  Milling  Machine  Company.  In  con- 
nection with  these  illustrations  the  student  should  note  not  only  the 
work,  but  also  the  shapes  of  the  cutters,  and  the  various  fixtures  and 
clamping  methods  used  to  hold  the  work  to  the  table. 

Slab-milling. — Fig.  577  illustrates  an  operation  called  slab-milling. 
The  cutter  is  of  the  inserted-tooth  type,  the  teeth  being  arranged  in 


408 


MACHINE-SHOP  TOOLS  AND  METHODS 


helical  lines.     While  some  distance  apart,  the  teeth  are  so  placed  as 
to  cover  the  whole  width  of  the  work  in  one  revolution.    The  principle 


Milling-cutter. 
FIG.  556. 


Milling-cutter  with  Nicked  Teeth. 
FIG.  557. 


Left-hand  End-mill. 
FIG.  558. 


End-mill  with  Center  Cut. 
FIG.  560. 


Interlocking 
Side-milling 

Cutter. 
FIG.  559. 


Side-milling  Cutter. 
FIG.  561. 


Spiral  End-mill. 
FIG.  562. 


Spiral  Shell  End-mill. 
FIG.  563. 


Face-milling  Cutter  with  Inserted  Teeth, 
FIG.  564. 


is  the  same  as  that  of  the  notched  cutter  of  Fig.  492.     The  advantage 
of  this  form  of  cutting-edge  has  been  referred  to  in  connection  with 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          409 


Angular  Cutters. 
FIG.  565. 


Involute  Gear-cutter 
FIG.  566. 


Side-milling  Cutter  with  Inserted  Teeth 


t^^   ^^%, 


Metal-slitting  Saw. 
FIG.  568. 


Twist-drill  Cutter. 
FIG.  569 


Screw-slotting  Cutter. 
FIG.  570. 


410 


MACHINE-SHOP  TOOLS  AND  METHODS 


Fig.  203  and  elsewhere  in  this  work.     The  pieces,  which  are  held  in  a 
special  chucking  fixture,  are  cast  iron  with  the  scale  on,  and  the  mill 


Epicycloidal  Gear-cutter. 
FIG.  571. 


FORM 

FIG.  575. 


Stocking  Cutter. 
FIG.  572. 


RADIAL 


FIG.  576. 


is  represented  as  removing  this  scale  at  a  cutting  speed  of  40'  per  minute, 
the  cut  being  about  l/&"  deep  by  81/4//  wide  and  the  feed  .252"  per 
turn  of  cutter. 


MILLING-MACHINES  AND   MILLING-MACHINE  WORK          411 


FIG.  577. 


FIG.  578 


412 


MACHINE-SHOP  TOOLS  AND  METHODS 


Gang-milling. — The  mill  or  milling-cutter  shown  in  connection  with 
Fig.  578  is  made  up  of  several  cutters,  and  for  this  reason  it  is  called 
a  gang-mill.  The  cutters,  which  are  5"  and  3"  diameter,  make  31  revo- 
lutions per  minute,  taking  a  cut  1/s//  deep  by  O1/*"  wide,  with  a  feed 


FIG.  579. 

of  .075"  per  turn.  The  5"  cutters  machine  the  pieces  a  short  distance 
down  the  sides 

The  same  pieces  are  inverted  in  Fig.  579,  and  the  sides  are  being 
cut  down  and  upper  edges  milled  in  one  operation.  The  large  mills 
are  13V2"  diameter  and  make  121/2  turns  per  minute,  the  feed  being 
.100"  per  turn. 

The  double  support  for  the  outer  end  of  the  arbor  in  the  last  two 
operations  is  worthy  of  notice. 

Slot -milling,  etc. — The  operation  in  Fig.  580  is  that  of  milling  a 
slot  in  the  oscillating  link  of  the  shaper  illustrated  in  Figs.  508  to  510. 
The  cutter  is  23/4"  diameter  and  takes  a  cut  Vis"  deep  by  23/4"  wide 
at  top  and  bottom  of  the  slot.  The  same  cutter  is  used  for  the  end  slot 
and  for  the  flat  surfaces  at  top  and  bottom  of  the  link. 

Fig.  581  shows  both  sides  of  the  link  being  milled  at  the  same  time 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          413 

with  face-mills.     The  method  of  squaring  the  link  in  a  special  V  block 
fixture  is  instructive. 


FIG.  580. 


FIG.  581. 


Milling  a  Gas-engine  Frame. — In  milling  the  casting  shown  in  Fig.  582 
the  table  is  fed  .102"  per  turn  of  cutter  during  the  time  that  the  large 
cutter  is  entering  the  work.  When  all  the  cutters  are  in  full  contact 
the  feed  is  dropped  to  .080".  This  method  results  in  a  saving  of  about 


414 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  583 


MILLING-MACHINES  AND  MILLING-MACHINE   WORK 


415 


15  per  cent.  The  wide  range  of  feeds  and  modern  quick  feed-changing 
mechanism  makes  this  and  greater  results  possible.  With  the  old 
cone-pulley  feeds  and  narrow  range,  in  some  work  there  was  no  feed 
even  approximately  right.  The^number  of  spindle  speeds  was  also 
inadequate.  The  consequence  was  a  serious  loss. 

Milling  Steel  Castings. — In  the  foregoing  examples  the  metal  operated 
upon  has  been  cast  iron.  Fig.  583  shows  a  gang-mill  machining  a  num- 
•ber  of  steel  castings,  the  latter  being  held  in  a  special  fixture.  The 
largest  cutters  are  51/2//  in  diameter  and  the  smallest  2" '.  The  mill  makes 
56  revolutions  per  minute,  giving  the  smallest  cutters  a  cutting  speed 
of  30'  per  minute.  The  depth  of  cut  is  about  3/32/x,  the  total  width 
of  milled  surface  being  5"  and  the  feed  .050"  per  turn. 


FIG    584. 

Milling  a  Dovetail  Slot  (Fig.  584).  —  The  work  in  this  case  is  a 
270-pound  steel  casting  in  which  it  is  required  to  cut  from  the  solid  dove- 
tail slots  ll/s"  deep  by  about  l5/g"  wide  at  the  outer  edge.  ^The  end 
mill  seen  on  the  table  is  first  used.  With  this  tool  a  rectangular  slot 


416 


MACHINE-SHOP  TOOLS  AND  METHODS 


iVs"  deep  by  l5/s"  wide  is  cut  at  a  surface  speed  of  36',  the  feed  being 
.012"  per  turn.  The  cutter  shown  in  the  spindle  finishes  the  slot.  In 
these  operations  the  work  is  fed  vertically,  and  in  addition  to  the  cut 
the  feed  mechanism  lifts  the  work  and  the  heavy  machine  parts. 

The  student  should  note  that  in  this  and  the  preceding  example 
a  lower  cutting  speed  is  used.  This  is  due  to  the  tougher  nature  of 
the  material. 

In  milling  steel,  wrought  iron,  etc.,  oil  or  some  cheaper  lubricant 
is  generally  used  and  the  piping  seen  just  above  the  cutter  is  for  this 
purpose. 

Milling  Keyways.  Methods  of  Holding  the  Shafts. — When  a  key- 
way  is  to  be  milled  the  full  length  of  a  shaft,  the  clamps  or  straps  which 
hold  the  shaft  must  be  so  arranged  as  not  to"  interfere  with  the  cutters. 


FIG.  585. 

Fig.  585  shows  a  fixture  in  which  two  shafts  are  simultaneously  milled, 
the  clamps  being  properly  arranged. 

The  side-straps  are  blocked  up  with  adjustable  studs  screwed  into 
the  clamps  and  held  by  a  check-nut.  This  very  convenient  expedient 
can  be  used  in  strapping  work  in  any  machine. 

When  two  opposite  keyways  are  required  in  the  same  shaft  the 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


417 


latter  may  be  quickly  adjusted  for  the  second  keyway  by  using  a  guide 
like  that  shown  under  the  right-hand  shaft. 

If  short  keyways  near  the  middle  of  the  shafts  are  wanted,  the  shafts 
may  be  held  by  two  straps  with*a  central  bolt  in  each  strap,  the  latter 
being  placed  so  as  to  clear  the  cutters.  No  blocking  is  needed  in  this 
case. 

In  many  cases  shafts  may  be  held  in  the  table  slots  by  straps  with- 
out any  special  fixtures. 

Emergency  Milling. — It  is  occasionally  necessary  to  mill  work  for 
which  no  regular  cutter  is  available.  In  such  a  case  a  fly-cutter  made 
on  the  principle  of  that  shown  in  Fig.  586  may  be  used.  The  cutter 


FIG.  586. 

may  be  made  of  rectangular  or  round  steel  and  held  in  a  miller  arbor 
by  set-screws  as  shown  or  by  a  key.  The  shapes  of  cutters  seen  between 
the  perspective  and  end  views  are  suggestive  of  what  may  be  done  in 
this  way.  These  cutters  are  not  economical,  but  they  may  be  very 
quickly  made,  and  their  use  is  justified  in  an  emergency. 

Boring  in  the  Miller. — Fig.  587  shows  how  a  simple  cutter  and  boring- 
bar  may  be  used  in  the  miller.     The  boring-cutter  is  shown  at  a.     In 
a   collar    at    c   are    two    cutters    for 
facing  the  work.     It  is  obvious  that 
drilling    and    reaming    may   also    be 
done  in  the  miller. 

Holding  Work  Without  Special 
Fixtures. — In  most  of  the  examples 
given  above  the  work  is  held  in  special 
fixtures.  The  use  of  bolts  and  straps 
for  clamping  work  on  the  miller  table  FIG.  587. 

being  substantially  the    same    as    in 

the  drilling-machine,  boring-machine,  and  planer,  it  seems  scarcely 
necessary  to  give  the  methods  in  this  connection.  However,  Fig. 
588  shows  three  castings  held  by  bolts  and  straps,  the  shape  of  the 


418 


MACHINE-SHOP  TOOLS  AND  METHODS 


pieces  being  such  as  to  facilitate  this  method.     It  will  be  noticed  thau 
the  outside  edges  of  the  castings  are  in  contact  with  strips  of  metal 


FIG.  588. 

fitting  one  of  the  table  slots.  This  simple  method  of  " lining  up"  work 
is  also  used  in  the  planer. 

In  the  above  work  the  8"  face-mill  is  taking  a  cut  about  l/8"  deep 
by  6"  wide  on  cast  iron,  the  cutting  speed  being  40'  per  minute  and 
the  feed  .138"  per  turn.  The  pressure  of  the  cut  tends  to  hold  the  work 
against  the  strips,  but  when  there  is  heavy  pressure  lengthwise  on  the 
table,  end-stops  may  be  necessary.  The  miller  lacks  the  holes  for  stop- 
pins  provided  in  the  planer-table,  but  in  most  cases  simple  straps  firmly 
bolted  to  the  table  will  answer.  Pasteboard  under  the  straps  will  pro- 
tect the  table  and  at  the  same  time  cause  the  straps  to  hold  more 
securely.  However,  when  the  point  of  contact  between  the  strap  and 
work  needs  to  be  high,  the  strap  may  be  held  on  wooden  blocks,  the 
latter  being  placed  with  the  grain  perpendicular  to  the  table. 

Vertical  Miller  Operations. — The  methods  of  holding  work  by  bolts 
and  straps  is  further  illustrated  in  Pigs.  589,  590,  and  591.  These 
illustrations  show  also  various  operations  in  the  Becker-Brainard 
Vertical  Miller. 

Fig.  592  shows  a  good  example  of  &>xet&ii  milling,  the  work  being 
held  on  an  arbor  supported  in  V  blocks.  The  blocks  hold  the  arbor 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


419 


parallel  with  the  table  and  the  milled  surfaces  are  therefore  true  with 
the  bore. 


FIG.  589. 


FIG.  590. 


FIG.  591. 


FIG.  592. 


Fig.  593  is  suggestive  of  the  possibilities  of  the  rotary  attachment. 
Hand-wheels  having  a  semicircular  rim,  worm-wheels,  and  much  other 
lathe  work  may  be  machined  in  this  manner. 


420 


MACHINE-SHOP  TOOLS  AND  METHODS 


Holding  Work  in  the  Vise.    Milling  Parallel  Pieces  of  Different 
Widths  with  Same  Pair  of  Cutters. — Much  of  the  small  work  machined 


FIG.  593. 


FIG.  594. 

in  the  miller  may  be  held  in  the  vise.     Fig.  594  shows  a  piece  thus  held. 
In  this  illustration  we  wish  to  call  special  attention  to  the  method  of 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          421 

adjusting  the  cutters.  The  position  of  the  latter  on  the  arbor  is  deter- 
mined by  the  number  and  lengfhs  of  the  detachable  collars.  These 
are  made  (preferably  of  tool  stegl  hardened  and  ground)  in  different 
lengths,  and  in  different  diameters  to  suit  the  arbors.  Collars  and 
cutters  are  held  by  the  nut  on  the  end  of  the  arbor,  the  latter  having  a 
taper  shank  to  fit  the  miller-spindle.  When  parallel  pieces  of  different 
widths  are  to  be  milled  the  same  pair  of  cutters  may  be  used  by  merely 
changing  the  length  of  the  collar  between  the  cutters.  The  illustration 
will  make  this  clear.  Thin  washers  are  useful  in  adjusting  the  cutters. 
The  Universal  vise  shown  in  Fig.  595  can  be  so  adjusted  as  to  hold 
work  at  any  angle.  The  angles  are  indicated  by  the  graduations. 


FIG.  595. 

Miller  vises  are  generally  made  with  a  tongue  fitting  the  table-slots. 
They  are  held  to  the  table  by  short  bolts. 

Wide-angle  Spiral  Attachment. — As  a  rule  an  attachment  for  given 
work  is  not  so  economical  in  its  operation  as  a  machine  specially  adapted 
to  that  work.  Nevertheless,  a  considerable  variety  of  attachments  are 
used  in  connection  with  the  horizontal  miller,  and  some  of  them  are  quite 
satisfactory.  A  good  idea  of  the  general  construction  of  most  of  these 
devices  may  be  obtained  by  a  study  of  the  wide-angle  spiral  attachment, 
a  sectional  view  of  which  is  shown  in  Fig.  596.  In  this  illustration  A  is 
the  box  frame,  B  an  arbor  fitting  the  miller-spindle,  C  a  miter-gear  keyed 
to  the  arbor  and  journaled  in  A,  D  another  miter-gear  meshing  with  C 
and  operating  E,  and  F  the  cutter-spindle  driven  by  worm  or  spiral  gears 
as  shown. 

The  perspective  view,  Fig.  597,  is  probably  that  of  a  smaller  size, 
but  it  is  a  good  representation  of  the  outside  appearance  of  this  attach- 


422 


MACHINE-SHOP  TOOLS  AND  METHODS 


ment.  The  method  of  securing  the  attachment  to  the  miller  and  swivel- 
ing  the  cutter-spindle  to  any  angle  in  a  horizontal  plane  is  clearly  indi- 
cated in  this  view.  The  figure  illustrates  the  operation  of  cutting  a 
spiral  gear. 

The  Vertical  Milling  Attachment  shown  in  Fig.  598  is  simpler  than 
the  spiral  attachment.     Its  spindle  and  head  may  be  swiveled  in  a  ver- 


FIG.  596. 


tical  plane  through  a  complete  circle  The  engraving  represents  a  41/2" 
cutter  taking  a  light  cut  on  cast-iron  pieces  which  have  been  previously 
roughed  out.  The  surface  speed  of  the  cutter  at  its  largest  diameter  is 
60'  per  minute,  the  feed  .252"  per  turn,  and  the  width  of  the  cut  43/16". 
Rack  Attachment. — Fig.  599  shows  a  rack-milling  attachment.  The 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          423 

spindle  is  horizontal,  but  it  is  placed  below  the  main  spindle  and  at  right 
angles  to  the  latter.  This  arrangement  admits  of  cutting  racks  several 
times  longer  than  would  be  possjfcle  with  the  main  machine.  The  cut 
represents  a  special  fixture  holding  a  long  rack  which  is  being  milled. 


FIG.  597. 

Slotting  Attachment. — For  tool-making  and  die-sinking  the  attach- 
ment shown  in  Fig.  600  is  a  valuable  addition  to  a  miller  outfit.  The 
interior  mechanism  of  this  attachment  is  quite  different  from  that  of 
Fig.  596,  and  the  lesson  that  it  furnishes  in  machine  design  may  justify 
the  addition  of  Figs.  601  and  602.  The  names  given  in  connection  with 
the  various  parts  render  a  lengthy  description  unnecessary.  The  attach- 
ment frame  is  secured  to  the  miller  and  overhanging  arm  on  the  same 
principle  that  the  arm  itself  is  held.  The  "  crank-disk,"  which  operates 
the  slotting-tool,  is  a  cylindrical  shell  keyed  to  the  miller-arbor 
and  journaled  in  the  attachment  frame.  On  the  outer  face  of  the  disk 
is  a  T  slot  in  which  the  crank-pin  is  adjusted  for  different  lengths  of 
throw.  The  tool-holder  may  be  swiveled  through  a  complete  circle  in  a 
horizontal  plane,  and  the  whole  attachment  may  be  swiveled  through 
20°  in  a  vertical  plane. 


424 


MACHINE-SHOP  TOOLS  AND  METHODS 


Among  other  milling  attachments  are  the  attachment  for  cutting 
internal  gears,  the  cam-cutting  attachment,  the  rotary  attachment,  and 
the  high-speed  attachment.  The  latter  is  a  device  by  which  very  small 
cutters  are  caused  to  run  faster  than  the  main  spindle  of  the  miller. 


FIG.  598. 

The  rotary  attachment  is  shown  in  Fig.  555  bolted  to  the  table  of  the 
vertical  miller.     It  is  shown  again  in  Fig.  593. 

Dividing  Head. — If  we  wish  to  distinguish  between  milling  attach- 
ments and  miller  attachments  the  dividing  head  should  be  classed  among 
the  latter.  This  is  the  device  used  in  the  miller  for  indexing,  i.e.,  making 
accurate  divisions  of  polygonal  figures  and  dividing  circles.  It  is  a  neces- 
sary adjunct  of  the  Universal  miller.  Before  considering  the  work  done  in 
connection  with  the  dividing  head  it  is  important  to  have  a  clear  under- 
standing of  the  construction  of  this  attachment.  In  Fig.  603  is  shown 
an  end  view  of  the  dividing  head  partly  sectioned  and  Fig.  604  shows  a 
vertical  section  through  the  center  of  the  spindle-bearing.  These  are 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK  425 


FIG.  599. 


FIG.  600. 


426 


MACHINE-SHOP  TOOLS   AND  METHODS 


FIG.  601. 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK  427 


FIG.  602. 


428 


MACHINE-SHOP  TOOLS  AND  METHODS 


cuts  of  an  old  design.     They  are  used  because  in  them  the  principle 
is  clearly  illustrated.     A  later  design  of  the  Brown  &  Sharpe  dividing 


FIG.  603. 

head  in  connection  with  the  foot-stock  is  shown  in  Figs.  605,  606,  607, 
and  608.      Referring  to  Figs.  603  and  604,  the  worm-wheel  G,  which  is 


FIG.  604. 

tightly  keyed  to  the  spindle  S,  has  40  teeth.  Meshing  with  G  is  the 
worm  W ,  tightly  secured  to  0.  Detachably  secured  to  T  (which  turns 
freely  on  0)  is  an  index-plate  R,  Fig.  603.  Each  machine  has  several 
of  these  plates,  and  each  plate  has  several  different  circles  of  holes  by 
which  various  divisions  of  circles  may  be  measured.  The  crank  J  is 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


429 


slotted  so  that  it  may  be  moved  radially  on  0  to  bring  the  pin  P  in  line 
with  any  circle  of  holes  on  R.     ^hen  adjusted  as  required,  J  is  held 


& 

tightly  on  0  by  the  nut  N.    The  gear  or  other  work  may  be  rotated  with 
the  spindle  S  by  revolving  J  independently  of  R.     In  this  case  the  pin 


430  MACHINE-SHOP  TOOLS  AND  METHODS 

P  is  withdrawn  and  inserted  again  for  each  tooth,  and  pin  F  1  holds 
JR  stationary.  This  method  is  used  in  simple  indexing.  The  work  may 
also  be  revolved  by  turning  J  and  R  together.  At  this  time  P  is  in  one 
of  the  holes  in  R  and  pin  F  1  is  withdrawn.  The  two  methods  com- 
bined are  used  in  compound  indexing. 

In  many  kinds  of  work  it  is  necessary  to  swivel  the  spindle  S.  It 
may  be  swung  around  on  the  axis  of  the  worm-shaft  and  clamped  by  a 
bolt  passing  through  the  circular  slot. 

Dividing-heads  have  been  much  unproved  since  that  of  Fig.  603 
was  designed.  The  head  illustrated  in  Fig.  605  has  in  addition  to  the 
index-plate  /  a  second  index-plate.  As  shown  at  C  in  the  sectional 
view,  Fig.  607,  this  plate  is  secured  by  screws  to  the  spindle.  The 
object  of  this  plate  is  to  provide  for  quick  indexing  in  certain  kinds  of 
work — grooving  taps  and  reamers,  for  instance.  In  this  direct  indexing 
the  worm  is  disconnected  from  the  worm-wheel  and  the  plate  is  turned 
by  hand.  Both  plate  and  spindle  may  be  locked  by  the  pin  D. 

Simple  Indexing. — Referring  again  to  Figs.  603  and  604,  the  gear  (or 
other  work)  being  placed  in  position,  one  revolution  of  /  causes  G  and 
the  gear  to  turn  1/40  of  a  revolution.  Now  if  40  be  the  required  number  of 
teeth  in  the  gear,  one  turn  of  /  will  give  the  correct  division  for  each 
tooth.  If  80  teeth  are  wanted,  one  half  revolution  of  J  is  correct.  It 
is  a  simple  matter,  therefore,  to  deduce  the  following  rule:  40  +  number  of 
teeth  in  gear  =  revolutions  of  J  for  each  tooth.  Let  it  be  required  to  cut  19 
teeth.  By  the  above  rule  4%9  equals  22/i9>  equal  revolutions  of  /.  In  this 
case  we  select  an  index-plate  with  a  19-hole  circle  or  some  multiple  of  19. 
Using  the  19-hole  circle  we  turn  the  crank  two  complete  revolutions 
and  then  move  it  two  spaces  more. 

To  obviate  mistakes  in  registering  the  fraction,  a  sector  is  used  in 
connection  with  the  index-plate.  An  end  view  of  this  sector  is  lettered 
S  l-S  2  in  Fig.  603,  but  it  is  more  clearly  shown  in  a  front  view  in  con- 
nection with  an  index-plate  in  Figs.  610  and  619.  In  adjusting  this 
sector  to  register  2/i9  the  two  limbs  S  l-S  2  are  swung  around  on  the 
shaft  until  just  2  spaces  (equaling  3  holes)  are  enclosed  between  the 
limbs;  a  snrll  screw  is  then  tightened,  holding  the  limbs  fast.  Now 
for  each  of  the  19  teeth  in  the  gear  the  crank  J  must  be  turned  two 
revolutions  plus  the  fraction  enclosed  by  the  sector. 

The  sector  should  always  be  pulled  around  by  the  advancing  limb; 
otherwise  its  adjustment  may  be  disturbed. 

Compound  Indexing. — It  sometimes  happens  that  we  wish  to  cut  a 
igear  with  some  number  of  teeth  that  cannot  be  divided  by  simple  indexing 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          431 

with  any  plate  on  hand.  We  then  have  recourse  to  what  is  termed 
compound  indexing.  Let  it  be  required  to  cut  96  teeth  by  this  method. 
According  to  the  rule  the  gear'' must  be  turned  40/96  of  a  revolution 
for  each  tooth.  One  of- the  plates  furnished  with  the  machine  has 
20  holes  in  the  outside  circle  and  18  in  the  next.  The  position  of  the 
pin  F  1,  Fig.  603,  is  the  same  distance  from  the  axis  of  0  as  the  18-hole 
circle,  and  generally  in  one  of  these  holes.  If,  now,  we  move  the  crank 
5  spaces  of  the  20-hole  circle,  withdraw  pin  F  1,  and  turn  J  with  R 
3  spaces  of  the  18  circle,  we  shall  move  the  gear  to  be  cut  5/2o  +  3/is 
=40/96  of  a  revolution. 

It  will  be  noticed  that  both  of  these  movements  were  in  the  same 
direction;  in  some  cases,  however,  we  cannot  get  the  right  division  in 
this  way,  but  have  to  move  the  crank  forward  too  much,  and  then 
make  the  correction  by  moving  the  index-plate  with  the  crank  back- 
ward. It  so  happens  that  the  96-tooth  gear  could  be  divided  by  both 
the  "plus  and  the  minus  methods"  so  to  speak.  We  shall  use  the  18  and 
20  circles  as  in  the  previous  case.  Starting  with  the  18-hole  circle  it 
will  be  necessary  to  take  such  a  fraction  of  that  circle  that  when 
40/96  is  subtracted  from  it  the  remainder  will  be  equivalent  to  some 
fraction  of  the  20-hole  circle.  The  process  in  this  case,  as  well  as  in 
the  former  case,  is  a  tentative  one.  If  we  take  9  holes  of  the  18  circle 
it  will  equal  48/96  revolutions  of  the  index-plate.  Now,  subtracting 
40/96  from  48/96  we  have  8/96  left;  but  we  find  this  is  not  equivalent 
to  any  fraction  having  20  for  a  denominator.  Therefore,  9  spaces  of 
the  18  circle  cannot  be  used.  Let  us  now  try  12  spaces  of  the  18  circle. 
12/is  equals  64/96  of  a  revolution  of  the  index-plate;  subtracting  40/96 
we  have  as  a  remainder  24/96-  24/96  equals  5/2o,  equals  5  spaces  in 
the  number  20  circle.  So  we  find  that  by  moving  the  index-plate 
and  crank  together  12  spaces  forward  in  number  18  circle  and  the 
crank  5  spaces  backward  in  the  20-hole  circle  we  turn  the  gear  40/96  of 
a  revolution,  which  was  found  by  the  rule  to  be  the  correct  division 
for  the  96-tooth  gear.  Thus  12/i8-5/2o=40/96- 

It  should  be  borne  in  mind  that  the  number  of  holes  to  be  enclosed 
with  the  sector  must  be  one  more  than  the  required  number  of  spaces. 

Some  dividing  heads  are  so  constructed  that  the  back-pin  F  1  may 
be  adjusted  radially.  With  such  an  arrangement  a  wider  range  of  divi- 
sions may  be  made. 

Differential  Indexing. — The  latest  indexing-heacls  made  by  the 
B.  &  S.  Manufacturing  Company  admit  of  a  new  differential  method 
of  indexing  in  addition  to  direct  or  plain  indexing.  By  this  differential 


432 


MACHINE-SHOP  TOOLS  AND  METHODS 


method  any  division  from  1  to  332  may  be  quickly  and  accurately  made. 
When  this  method  is  used  the  index-plate  and  main  spindle  of  the  head 
are  connected  by  a  train  of  gears.  The  effect  of  this  arrangement  is 
to  cause  the  plate  to  turn  at  the  same  time  the  crank  is  being  rotated. 
If  one  idler  or  intermediate,  as  at  D  in  Fig.  609,  be  used,  the  index-plate 


tvill  turn  in  the  direction  of  the  crank.  rlhe  use  of  two  idlers  causes 
the  plate  to  turn  in  the  opposite  direction  to  that  of  the  crank.  Because 
of  this  rotation  of  the  index-plate  we  cannot  use  40  in  the  computations 
p,s  the  constant  numerator,  but  must  use  some  other  numerator  or 
"spacing  number."  What  this  new  numerator  shall  be  for  any  given 
combination  of  gearing  will  depend  upon  whether  one  or  two  idlers  are 
used  and  the  proportions  of  the  gears.  The  index-crank  makes  40 
iurns  to  1  of  the  spindle,  and  with  equal  numbers  of  teeth  in  gears  E 
and  C  the  index-plate  will  make  1  turn  to  1  of  the  spindle.  Hence  the 
following  rules: 


.A    teeth  in  E  . ..      . 

40  —  7 — -j— •: — ~=  numerator  when  one  idler  is  used: 
teeth  in  C 


40  + 


teeth  in  E 
teeth  in  C 


two  idlers  are  used. 


(D 


(2) 


The  manufacturers  furnish  with  the  dividing-head  a  table  giving 
the  changes  for  both  plain  and  differential  indexing,  including  all  divi- 
sions from  1  to  382.  The  gears  and  index-plates  furnished  with  the 
machine  cover  this  range,  but  extras  can  be  supplied.  For  131  divisions 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


433 


the  table  calls  for  gears  with  28  and  40  teeth  for  E  and  C  respectively, 
and  one  idler,  the  movement  of  index-crank  being  6  spaces  in  the  20-hole 

28 
circle.     Let  us  test  these  proportions.     By  rule  (1)  40—  -~;  =  393/iQ= 

new  numerator.     Having  this  new  numerator,  we  proceed  exactly  as 


with  the  older  design  of  dividing-head.      Thus 


39.3 


=  ™  =  6  spaces  m 


131      20 

the  20-hole   circle   as  required.     The  equality  of  these  two  fractions 
may  be  quickly  proved  by  reducing  both  to  decimals. 

In  some  cases  it  is  necessary  to  use  compound  gearing.  Fig.  610 
shows  the  gears  compounded  and  one  idler  added.  As  the  gears  on 
the  compound  stud  affect  the  direction  of  rotation  of  the  index-plate, 
a  combination  like  that  of  Fig.  610  must  be  computed  for  two  idlers. 


FIG.  bid 

The  other  effect  of  compounding  must,  of  course,  be  also  considered. 
Using  the  letters  on  the  gears  as  symbols  of  the  numbers  of  teeth,  the 
equations  for  the  two  cases  are  as  follows: 

/  F1      F  \ 

40  —  (  77-  X  TT  )  =  numerator  when  one  idler  is  used ;     .     .     (3) 
Or      C  / 


40+   ~XV   - 

,G        C 


two  idlers  are  used.       .     (4) 


For  374  divisions  the  table  calls  for  the  arrangement  shown  in  the 
illustration.  The  gears  required  are  the  following:  Gear  on  spindle  (E), 
56  teeth;  first  gear  on  stud  (F),  64  teeth;  second  gear  on  stud  (G), 


434  MACHINE-SHOP  TOOLS  AND  METHODS 

32  teeth;   gear  on  worm  (C),  72  teeth;   idler-gear  (D),  24  teeth.     The 

2 
movement  of  the  index-crank  is  given  as  --^==two  spaces  in  the  18-hole 

lo 

circle.      The  idler  D  does  not  affect  the  ratio.     Formula  (4)  applies 

(prf*          /*  A  \  K  A 

—  X^j=40  +  ,™  =  415/9=new    numerator, 

and  •  Q>7{9==2/18  =  movement  of  index-crank  as  required. 

o  i  4 

Computing  Change-gears  for  Cutting  Spirals. — In  the  common 
spur-gear  all  the  elements  of  the  teeth  are  parallel  to  the  axis  of  the 
gear.  In  the  spiral  gear  the  teeth  form  helical  grooves  around  the  gear- 
blank.  The  spur-gear  is  stationary  under  the  cutting,  except  that  it 
is  fed  in  a  straight  line  to  the  cutter.  The  spiral  gear,  in  addition  to 
the  feed,  is  given  a  rotary  motion  on  its  axis.  The  linear  advance  or  feed 
of  the  gear  to  one  revolution  (although  most  spiral  gears  are  too  short  to 
make  a  revolution  for  each  tooth)  is  termed  the  lead. 

Fig.  611  shows  an  end  view  of  an  old  dividing-head.  The  screw  which 
feeds  the  table  is  shown  in  cross-section  marked  S  2.  This  feed-screw  is 
operated  by  the  regular  feed  mechanism,  and  the  blank  to  be  cut  is 
rotated  by  a  train  of  gears  the  first  of  which  is  keyed  to  this  screw, 
the  last  being  the  miter-gear  T  referred  to  in  connection  with  Fig.  603. 
The  other  miter-gear  having  immediate  connection  with  T  is  on  the 
inner  end  of  shaft  S  1  in  Fig.  611.  This  plate  shows  the  train  of  gears 
connected  ready  to  cut  a  spiral.  The  first  of  these  gears,  marked  G  1,  is 
called  gear  on  screw;  the  second,  G2,  is  first  gear  on  stud;  the  third, 
G  3,  is  second  gear  on  stud;  and  the  fourth,  G  4,  is  called  gear  on  worm. 
The  table  (and  of  course  the  gear-blank  with  it)  is  set  to  an  angle  con- 
forming to  the  angle  of  the  spiral  to  be  cut,  and  the  combined  rotary 
motion  and  linear  advance  of  the  gear-blank  give  the  helical  curve  to 
the  teeth.  The  principles  involved  are  the  same  as  in  screw-cutting  in 
the  lathe,  and  the  change-gears  are  computed  in  practically  the  same 
manner. 

Now.  let  it  be  required  to  cut  a  spiral  of  36"  lead.  The  screw  S  is 
of  1/4//  lead.  It  will,  therefore,  have  to  make  4x36  =  144  revolutions 
to  advance  the  miller-table  and  gear-blank  36".  The  wonn- wheel, 
as  we  have  already  seen,  has  40  teeth,  and  as  one  turn  of  the  worm 
moves  the  worm-wheel  only  one  tooth,  the  worm-shaft  0,  Fig.  603,  will 
have  to  make  40  turns  to  144  turns  of  the  screw.  With  a  worm-gear  of 
144  teeth  and  a  gear  of  40  teeth  on  the  screw,  or  any  two  gears  of  this 
proportion,  we  could  cut  the  spiral;  but  we  have  not  these  gears.  We 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


435 


shall,  therefore,  have  to  use  such  gears  as  are  furnished  with  the  machine. 
Among  the  latter  gears  are  gears  with  32,  40,  64,  and  72  teeth.  The 
machine  is  designed  to  use  compound  gearing,  and  we  may  compute  the 
required  gears  by  the  following  formula,  in  which  L  equals  the  lead  of 


FIG.  611. 

the  required  spiral,  4  the  revolutions  of  S  2  to  1"  advance  of  table,  40 
the  teeth  in  the  worm-wheel,  G  1  number  of  teeth  in  gear  on  screw, 
G  2  number  of  teeth  in  first  gear  on  stud,  G  3  number  of  teeth  in  second 
gear  on  stud,  and  G  4  number  of  teeth  in  worm-gear.  The  positions  of 
these  various  gears  will  be  clearly  understood  by  referring  to  Fig.  611. 


The  formula  is: 


LX4_G3XG4 
40    ~GIXG2' 


L  equals  36  in  this  case,  so  the  formula  becomes 
G3XG4    36X4    Lead 


G1XG2       40 


10 


436 


MACHINE-SHOP  TOOLS  AND  METHODS 


If  we  select  40  and  64  for  the  first  two  gears  we  must  divide  the 
fraction  40/i44  by  40/64  to  find  the  mating  gears.  Dividing  thus  we 

40      64       1 
nave  TJI  x/m=oTr-     The  worm-gear  must  then  be  2x/4  times  as  large 

144      4U      £  /4 

as  its  mating  gear.  Multiplying  32  by  2l/±  we  have  72  for  G  4  or  the 
worm-gear.  The  gears  complete,  then,  for  cutting  a  36"  spiral  are  40, 
64,  32,  and  72,  answering  to  G  1,  G  3,  G  2,  and  G  4  respectively. 

Milling  Bolts  and  Nuts  in  Connection  with  Dividing-head. — One  of 
the  simplest  operations  in  connection  with  the  dividing-head  is  that  of 
milling  bolt-heads  and  nuts.  In  milling  a  bolt-head  the  bolt  would 
generally  be  held  between  the  centers  of  the  dividing-head  and  foot-stock. 
The  latter,  which  is  shown  in  Fig.  606,  is  used  very  much  the  same  as  the 
tail-stock  of  a  lathe.  The  bolt  may  also  be  driven  by  a  lathe-dog,  as  in 
the  lathe. 

When  a  lot  of  nuts  are  to  be  milled,  a  number  of  them  are  milled  at 
one  time.  For  this  purpose  they  are  placed  upon  a  special  plain  arbor 
and  held  fast  between  a  shoulder  on  the  arbor  and  a  nut  on  its  end,  the 
arbor  being  held  between  centers  as  in  the  previous  case.  Figs.  612  to  614 


FIG.  612. 


FIG.  613. 


FIG.  614. 


show  three  different  cutters  and  methods  for  milling  such  work.     The 
straddle-mill,  Fig.  612,  is  of  course  the  quickest  for  shapes  having  an  even 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          437 

number  of  sides.  One  method  of  adjusting  the  work  for  the  straddle- 
mill  is  to  raise  the  knee  high  enqugh  to  bring  the  arbor  between  the  two 
cutters,  and  then  make  the  spacgg  between  the  arbor  and  the  sides  of 
the  cutters  equal. 

Grooving  taps  and  reamers  is  another  class  of  work  generally 
milled  in  connection  with  the  dividing-head.  The  proportions  of  the 
grooves  have  been  referred  to  elsewhere  in  this  book.  The  indexing  for 
such  work  is  rather  slow  if  the  regular  index-plate  be  used.  Thus  a 

40 

4-groove  tap  requires  —  =  10  turns  of  the  plate  for  each  groove.     As  has 

been  intimated,  such  spacing  as  is  needed  for  nuts,  reamers,  etc.,  can  be 
done  very  quickly  by  the  plate  on  the  spindle. 

Micrometer  Measurements  in  the  Miller. — The  micrometer-disks,  or 
dial-plates  on  the  feed-screws  of  the  miller  afford  a  very  convenient  means 
of  measuring  depth  of  cut,  etc.  These  disks  are  generally  graduated  to 
thousandths  of  an  inch  and  sometimes  to  half  thousandths.  Thus  if  re- 
quired to  mill  \"  round  stock  to  hexagonal  shape,  Vs"  across  flats,  by 
the  method  of  Fig.  613,  we  would  first  raise  the  knee  until  the  stock  just " 
touched  the  revolving  cutter.  This  may  be  called  the  zero  position  of  the 
work. 

To  correspond  with  this  we  set  the  micrometer-disk  (or  pointer)  to  its 
zero  position.  Having  made  these  adjustments  the  knee  is  next  raised 
until  the  pointer  indicates  62x/2  thousandths,  when  the  milling  may  be 
begun.  The  same  principles  will,  of  course,  apply  in  adjusting  the  other 
feed  movements.  In  all  cases  the  backlash  must  be  taken  up  before 
adjusting  the  pointer. 

Special  Dog  for  Taper-milling. — In  milling  taper  work  between  centers 
the  dividing-head  may  be  rotated  slightly  to  lower  its  center,  or  the  center 
in  the  foot-stock  may  be  raised.  In  either  case  the  common  lathe-dog, 
on  account  of  the  changing  contact  of  its  tail  with  the  slot  of  the  driver, 
causes  irregular  spacing  and  gives  trouble  otherwise.  A  dog  made  like 
that  of  Fig.  615  should  be  used.  The  tail  of  this  dog  is  cylindrical,  and 
is  offset  so  that  the  dog  may  be  so  adjusted  as  to  cause  the  center  line 
of  the  cylindrical  part  to  pass  through  the  center  of  contact  between 
the  work-center  and  the  dividing-head  center.  It  is  important  also 
that  the  slot  in  the  driver  be  parallel  and  adjustable.  The  driver 
shown  in  the  illustration  meets  the  requirements.  The  upper  illustration 
is  given  merely  to  indicate  the  difficulty  in  using  a  common  dog. 

In  some  instances  one  end  of  the  work  is  driven  in  a  chuck  screwed 
on  the  end  of  the  dividing-head  spindle.  In  such  a  case  special  care 


438 


MACHINE-SHOP  TOOLS  AND  METHODS 


is  required  to  have  the  spindle  in  exact  alinement  with  the  foot-stock 
center.  The  adjustment  provided  in  the  dividing-head  and  foot-stock 
is  sufficient  for  ordinary  tapers. 


FIG.  615. 

Taper  Attachment  for  the  Miller. — When  much  taper  work  is  to 
be  done  in  the  miller  an  attachment  like  that  of  Fig.  616  will  be  advan- 
tageous. The  shank  of  the  center  seen  at  the  left  end  of  the  attach- 
ment fits  the  taper  socket  of  the  dividing-head  spindle.  The  other 
end  is  held  in  the  slotted  knee-plate  as  shown.  The  attachment  carries 
its  own  foot-stock,  which  is  longitudinally  adjustable.  This  device 


FIG.  616. 

may  be  angled  to  the  extent  of  10°,  and  the  alinement  of  the  centers 
will  in  nowise  be  disturbed.  " 

Milling  Abrupt  Angles. — In  milling  abrupt  angles  the  foot-stock 
is  not  used.  In  some  cases  angular  work  is  held  in  the  chuck;  in  other 
cases  it  may  be  held  On  an  arbor  the  shank  of  which  fits  the  head 
spindle.  The  latter  method  is  illustrated  in  Figs.  617  and  618. 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


439 


The  Use  of  Chucks  in  the  Miller. — As  intimated  the  chuck  is  used  to 
some  extent  in  connection  with.. the  dividing-head.  The  work  gripped 
in  the  chuck  is  principally  of"  small  diameter  and  the  Universal  chuck 
is  generally  preferred.  ^ 

r 


FIG.  617.  FIG.  618. 

The  draw-in  chuck  as  used  in  the  lathe  has  been  described  elsewhere. 
Fig.  619  shows  this  chuck  as  adapted  to  the  spindle  of  the  dividing- 
head.  Small  rods,  screws,  etc.,  may  be  very  quickly  and  accurately 
milled  in  connection  with  this  chuck.  For  instance,  if  required  to 
cut  slots  in  a  small  number  of  screw-heads,  the  screws  might  be  gripped 
one  at  a  time  in  this  device  by  merely  tightening  the  hand-wheel,  the 
slots  being  cut  by  feeding  the  knee  vertically  to  the  revolving  cutter. 
However,  when  a  large  number  of  screws  are  to  be  slotted  the  work 
can  be  performed  more  economically  in  a  special  fixture  which  holds  a 
number  of  screws.  Fig.  619  is  taken  from  an  article  by  A.  L.  Monrad 
in  "  American  Machinist,"  vol.  27,  page  153. 

Selecting  Gear-tooth  Cutters. — In  cutting  a  gear  it  is  necessary  to 
know  the  pitch  and  number  of  teeth  in  the  gear  in  order  to  select  the 
cutter.  The  gear-tooth  cutters  generally  used  are  made  according 
to  the  Brown  &  Sharpe  system.  In  the  involute  system  eight  cutters 
are  required  for  each  pitch.  The  range  covered  by  each  cutter  is  given 
in  the  following  table: 

No.  1  will  cut  wheels  from  135  teeth  to  a  rack 


55 
35 
26 
21 
17 
14 
12 


134  teeth 

54  " 

34  " 

25  " 

20  " 

16  " 

13  " 


440 


MACHINE-SHOP  TOOLS  AND   METHODS 


In  the  epicycloidal  system  there  are  twenty-four  cutters  to  a  set. 
The  first  cost  of  these  cutters  is,  therefore,  greater  than  that  of  the  in- 
volute. Gears  cut  with  an  involute  cutter  have  the  further  advantage 


American  Machinist 


FIG.  619. 


that  they  do  not  necessarily  require  such  an  exact  adjustment  of  the 
distance  between  shaft-centers  as  do  epicycloidal  gears.  For  these 
reasons  epicycloidal  gears  are  in  a  large  measure  being  superseded  by 
the  involute. 

The  pitch  of  a  gear  is  designated  in  two  ways :  first,  it  means  the 
distance  between  centers,  measured  on  the  pitch-circle,  of  two  adjacent 
teeth.  This  is  termed  the  circular  pitch.  Second,  it  means  the  num- 
ber of  teeth  in  the  gear  to  each  inch  of  its  pitch-diameter.  This  is  the 
diametral  pitch.  We  shall  use  the  latter  definition  here. 

The  cutter  which  is  right  for  a  spur-gear  is  too  thick  for  a  bevel-gear 
of  the  same  pitch.  Cutters  for  bevel-gears  are  made  on  the  assumption 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


441 


that  the  length  of  the  tooth-face  is  not  greater  than  one  third  the  distance 
from  its  outer  end  to  the  intersection  of  the  axes  of  the  two  shafts. 
Cutters  for  longer  faces  will  be  m*de  to  order.  In  selecting  a  cutter 
for  a  bevel-gear  we  do  not  make  use  of  the  actual  pitch-diameter,  but  a 
diameter  equal  to  twice  the  back-cone  radius  ab  for  the  large  gear,  and 
twice  be  for  the  small  gear  (see  Fig.  620).  If  be  equals  2"  and  the  gear 


FIG.  620. 

is  to  have  12-pitch  teeth,  we  should  select  a  cutter  for  4X12  =  48  teeth. 
By  reference  to  the  table  it  will  be  seen  that  a  No.  3  cutter  would  be 
required.  For  this  gear,  therefore,  we  would  order  a  No.  3,  12-pitch 
bevel  cutter.  The  large  gear  would  require  a  different  number  of  cutter. 
The  depth  of  the  tooth  space  must  also  be  known.  This  equals 

2  157 

'         when  P  equals  the  diametral  pitch.     The  depth  of  space  in  the 


above  gear  would  be 


2.157 
12 


=  .180".     This  is  the  depth  at  the  outer  or 


larger  end  of  the  tooth.     It  is  also  the  depth  in  a  spur-gear,  the  space 
in  such  gears  being  of  equal  depth  at  each  end  of  the  tooth. 

Cutting  a  Spur-gear  in  the  Universal  Miller. — The  term  "spur"  is  a 
general  term  applied  to  a  gear  whose  tooth  elements  are  parallel  to  the 
axis  of  rotation  of  the  gear.  Gears  shown  in  Figs.  621  and  622  are  spur- 
gears.  There  are  two  ways  of  holding  the  gear  while  cutting  the  teeth. 
First,  it  may  be  driven  tightly  on  an  arbor  and  caused  to  revolve  with 
the  dividing-head  spindle  by  one  end  of  the  arbor  fitting  a  taper-hole 
in  the  dividing-head  spindle.  Second,  the  gear  may  be  driven  on  an 
arbor  which  is  supported  between  the  dividing-head  and  foot-stock,  as 
in  a  lathe.  In  this  case  the  tail  of  the  dog  engages  with  a  slot  in  the 
face-plate  or  driver,  and  the  latter  is  provided  with  a  set-screw  which  is 


442  MACHINE-SHOP  TOOLS  AND  METHODS 

so  adjusted  against  the  tail  of  the  dog  as  to  prevent  any  "play"  or 
shake  of  the  dog  and  arbor.  Any  looseness  at  this  point  will  cause 
irregular  spacing  of  the  gear- teeth. 

As  indicated  elsewhere,  the  cutter  is  carried  by  an  arbor  fitting  in 
the  socket-hole  in  the  end  of  the  miller-spindle,  its  position  on  this  arbor 
being  regulated  by  slip-collars.  The  gear-blank  should  be  so  placed  in 
relation  to  the  cutter  that  a  vertical  plane  at  right  angles  to  the  axis 
of  the  cutter-arbor  shall  pass  through  the  centers  of  the  cutter  and  gear 
axis,  as  shown  in  Fig.  626.  This  is  done  by  so  adjusting  the  clamp-bed 
on  the  knee  as  to  bring  the  cutter  central  with  a  center  line  on  the 
foot-stock,  or  with  a  mark  on  the  dividing-head  when  the  foot-stock  is  not 
used.  The  knee  is  next  adjusted  vertically  until  the  cutter,  while  re- 
volving, will  just  touch  the  top  of  the  gear-blank.  This  is  the  zero 
position  of  the  cutter.  The  vertical  travel  of  the  knee  is  measured  on 
a  dial-plate,  as  was  explained,  and  the  dial-pointer  should  now  be  set 
at  zero  to  agree  with  the  position  of  the  cutter.  The  table  should  next 
be  moved  lengthwise  to  take  the  gear  from  under  the  cutter,  and  by 
means  of  the  hand-wheel  E,  Fig.  546,  the  knee  should  be  raised  a  dis- 
tance corresponding  to  the  depth  the  gear  is  to  be  cut.  In  adjusting 
the  knee  its  gib-screws  should  be  slackened  no  more  than  necessary  to 
permit  freedom  of  movement.  If  too  loose  the  screws  will,  when  tightened, 
raise  the  knee  slightly  and  thus  alter  the  previous  setting. 

In  order  to  insure  that  the  lost  motion  between  the  vertical  screw 
and  nut  shall  be  downward,  the  last  movement  of  the  crank  should  be  in  the 
direction  to  raise  the  knee.  If  this  is  not  properly  attended  to  the  reading 
on  the  dial  will  be  unreliable.  The  dial  for  vertical  adjustment  is  grad- 
uated in  thousandths,  and  a  complete  turn  of  the  dial-finger  generally 
equals  10%ooo".  The  depth  for  cutting  a  12-pitch  gear  is  18%0oo";  the 
movement  for  this  gear  should,  therefore,  be  I80/ioo  revolutions  of  the 
dial-finger. 

Having  properly  mounted  the  gear  and  having  made  the  adjustment 
as  indicated  we  are  ready  to  take  the  first  cut.  This  is  done  by  slowly 
feeding  the  gear  against  the  revolving  cutter  a  distance  equal  to  the 
face  or  thickness  of  the  gear  plus  clearance  at  each  end.  The  table  is 
now  quickly  returned  to  the  starting-point  and  the  gear  indexed  for 
the  next  cut.  Care  should  be  taken  that  the  clearance  on  the  entering 
end  is  such  that  during  the  time  the  gear  is  being  indexed  or  turned 
for  the  next  cut  it  will  not  come  in  contact  with  the  cutter.  The  above 
operation  is  repeated  for  each  tooth  in  the  gear,  and  while  turning  the 
indexing  crank,  caution  should  be  observed  to  prevent  the  pin  P  (Fig. 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          443 

603)  from  striking  and  moving  the  sector;  otherwise  an  error  in  the 
indexing  would  result.  It  should^tie  noted  also  that  the  holes  enclosed 
between  the  limbs  of  the  sector  mu&t  always  be  one  more  than  indicated 
by  the  fraction  measured. 

Cutting  Large  Gears.     Blocking  up  the  Centers. — It  is  sometimes 
necessary  to  cut  a  gear  of  so  large  a  diameter  that  the  gear  would  strike 


FIG.  621. 

the  miller-frame  if  carried  on  a  horizontal  arbor.  In  such  a  case  the  foot- 
stock  may  be  dispensed  with  and  the  gear  be  held  on  an  arbor  in  the 
dividing-head  spindle  as  shown  in  Fig.  621.*  In  milling  a  gear  by  this 
method  the  pressure  of  the  cut  should  be  supported.  The  support  should 
preferably  be  clamped  to  the  table  and  its  point  of  contact  with  the 
work  oiled,  so  that  it  will  not  be  disturbed  by  the  rotation  of  the  gear. 

*  This  cut  illustrates  an  article  by  Geo.  J.  Meyer  in  "American  Machinist,'* 
vol.  26,  page  1115. 


444 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  large  back-gears  on  the  miller  shown  in  Fig.  552  were  cut  on  a  small 
miller  by  the  above  method. 

The  long  lever  and  weight  shown  in  connection  with  Fig.  621  were 
used  to  counterbalance  the  weight  of  the  miller  knee,  table,  etc. 

Fig.  622  illustrates  another  method  of  cutting  large  gears.  In  this 
case  the  gear  is  held  between  centers,  but  it  is  raised  above  the  cutter. 


FIG.  622. 

The  dividing-head  and  foot-stock  shown  are  of  simple  construction, 
and  are  called  plain  index  centers. 

The  plan  of  blocking  up  the  centers  is  suggestive  of  an  expedient  that 
is  often  adopted  when  the  centers  are  too  low. 

Gears  of  average  pitch  are  commonly  cut  with  one  traverse  of  the 
cutter  for  each  space.  The  author  has  known  gears  as  coarse  as  3-pitch 
to  be  cut  in  this  way.  Many  mechanics,  however,  prefer  to  take  two 
cuts.  The  cutters  last  longer  and  do  better  work  if  kept  sharp. 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK 


445 


Cutting  Worm-wheels. — Fig.  623  shows  a  perspective  view  of  a  worm 
and  worm-wheel,  in  which  G  is  the-  wheel  and  W  the  worm.  It  will  be 
seen  that  the  teeth  form  an  acute  angle  with  the  bore  of  the  wheel,  and 


FIG.  623. — Worm  and  Worm-wheel. 

that  they  are  made  concave  to  conform  to  the  thread  on  the  worm.  To  cut 
these  teeth  two  cutters  are  commonly  used,  the  first  being  a  disk-cutter, 
as  was  used  in  cutting  the  spur-gear.  In  selecting  this  cutter  we  do 
not  consult  the  table,  but  use  any  cutter  which  will  leave  the  right  amount 
for  the  hob.  The  latter  is  a  kind  of  screw  with  cutting-edges  somewhat 


446 


MACHINE-SHOP  TOOLS  AND  METHODS 


like  a  tap  (see  Fig.  624).  The  disk-cutter  teeth  must  be  thinner  than 
.the  teeth  or  thread  on  the  hob  in  order  to  leave  some  metal  for  finish- 
ing with  the  hob;  and  in  using  the 
disk-cutter  the  table  must  be 
swiveled  to  an  angle  which  agrees 
with  the  angle  on  the  worm- 
thread. 

This  angle  may  be  determined 
by  drawing  a  triangle  the  base  of 
which  is  equal  to  the  lead  of  the 
worm-thread  and  the  altitude 
equals  the  pitch  circumference  of 
the  worm.  The  angle  formed  by 
the  hypotenuse  and  the  altitude  is 
FIG.  624.  the  angle  to  which  the  table  should 

be  swiveled.     As  the  first  cutter 

merely  roughs  out  the  teeth  a  close  approximation  to  the  angle  will  answer. 
Most  of  what  was  said  in  connection  with  spur-gears  will  apply  equally 
well  to  worm-wheels.  The  wheel,  however,  must  be  held  on  an  arbor 
between  centers  according  to  the  second  method  described.  The  re- 
lation of  wheel  and  cutter  is  shown  in  Figs.  625  and  626,  and  having 
made  these  adjustments  the  next  thing  is  to  swivel  the  table  to  the 
required  angle  and  then  raise  the  knee  until  the  revolving  cutter  will 
just  touch  the  two  corners  of  the  wheel  as  shown  at  EE,  Fig.  625.  Next, 
the  table  gib-screws  are  locked  and  the  dial-pointer  set  at  zero,  when  the 
teeth  may  be  cut.  In  this  operation  we  do  not  feed  the  table,  but  raise 
and  lower  the  knee  the  required  distance  for  each  tooth. 

There  is  or  should  be  a  line  on  the  face  of  the  column  where  the  knee 
slides  to  indicate  when  the  center  of  the  dividing-head  spindle  is  in  the 
same  horizontal  plane  as  the  center  of  the  miller-spindle.  The  depth  of 
the  tooth-space  is  determined  by  raising  the  knee  until  the  distance 
between  the  measuring  surface  on  the  knee  and  the  center  line  agrees 
with  the  distance  between  shaft-centers  as  given  on  the  drawing.  For 
the  roughing  cut  the  wheel  should  be  cut  to  within  about  1/64//  of  the 
final  depth. 

Robbing  the  Teeth. — After  cutting  all  the  teeth  in  this  manner  we 
take  the  disk-cutter  and  arbor  out  of  the  miller-spindle  and  use  the  hob, 
It  is  held  on  the  arbor  in  the  same  manner  that  the  disk-cutter  is  held. 
As  the  threads  on  the  hob  are  of  the  same  angle  as  the  worm  which  is  to 
operate  the  wheel,  the  table  must  now  be  swiveled  back  to  its  normal 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK  447 

position  at  zero.  In  bobbing  the  teeth  the  wheel  is  caused  to  turn  by 
the  interlocking  of  the  hob  and  wheel-teeth  as  shown  in  Fig.  627.  There- 
fore we  do  not  need  the  index-plate  for  dividing.  To  permit  the  wheel  to 
turn,  the  dog  is  removed  from  thfe  gear-arbor.  Before  starting  the  hob 


-AAAAA/V 

^ 

/\AAAA  A/ 

FIG.  625. 


FIG.  626. 


FIG.  627. 


the  knee  is  raised  until  the  thread  of  the  hob  engages  with  the  rough- 
cut  teeth  in  the  wheel.  The  machine  is  then  started,  and  during  the  first 
two  or  three  revolutions  of  the  wheel,  or  until  the  hob-thread  matches 
fairly  with  the  wheel,  the  wheel  is  helped  around  by  hand.  Having  made 
a  chalk-mark  on  the  wheel,  the  operator  feeds  the  knee  up  a  small  amount 
for  each  revolution  of  the  mark,  and  continues  this  process  until  the 
teeth  are  cut  the  required  depth. 

Worm-wheels  are  sometimes  cast  without  the  helical  lines  of  the  teeth, 
and  they  may  be  cut  with  the  disk-cutter  alone,  but  the  area  of  the 
tooth  contact  in  these  wheels  is  considerably  lessened,  and  consequently 
they  will  not  be  so  durable. 

When  large  quantities  of  worm-wheels  are  wanted  they  may  be 
made  more  economically  in  a  special  machine.  Such  machines  are  so 
constructed  that  by  a  train  of  gears  the  worm-wheel  is  caused  to  rotate 
in  unison  with  the  hob.  When  this  method  is  followed  the  preliminary 
roughing  cut  with  the  disk  is  dispensed  with. 

Cutting  Teeth  in  Bevel-gears. — Fig.  628  shows  a  miter-gear  mounted 
on  an  arbor  in  the  dividing-head  spindle,  the  dividing-head  being  the 
old  design  shown  in  Figs.  603  and  604.  (It  should  be  explained  in  this 
Connection  that  a  pair  of  gears  of  the  same  diameter  and  angles  whose 


448  MACHINE-SHOP  TOOLS  AND  METHODS 

axes  intersect  at  right  angles  are  called  miter-gears.)  The  foot-stock 
cannot  be  used  in  cutting  this  gear.  To  avoid  excessive  deflection,  the 
gear  should  be  placed  close  to  the  end  of  the  dividing-head  spindle.  It  is 
held  on  the  arbor  by  a  nut.  If  the  gear  be  of  such  a  size  and  angle  that 
the  nut  would  interfere  with  the  cutter,  the  nut  may  be  either  reduced 
in  thickness  or  omitted.  In  the  latter  case  the  arbor  should  fit  the  gear 
sufficiently  tight  to  be  held  by  friction. 

The  gear  must  be  set  central  under  the  cutter  as  in  the  case  of  the 
spur-gear.  The  dividing-head  is  graduated  along  the  edge  A,  and  it 
must  be  set  to  the  cutting  angle,  which  angle  is  given  on  the  drawing. 
When  thus  adjusted  it  is  clamped  by  the  nut  N.  The  side,  top,  and  bot- 
tom lines  of  the  teeth  converge  in  C,  and  consequently  when  the  gear 
is  set  to  the  cutting  angle  the  face  HF  will  not  be  horizontal.  When 
the  cutter  is  in  the  zero  position  its  center  will  be  in  the  same  vertical 
plane  as  is  the  highest  part  of  the  edge  H,  as  shown  in  Fig.  628.  To  find 
this  position  the  cutter  is  rotated,  and  while  the  table  is  fed  back  and 
forth  about  one  half  inch  the  knee  is  raised  until  the  cutter  touches  at  H. 
Next  the  table  is  moved  in  the  direction  of  arrow  7  and  the  knee  raised 
the  required  depth  of  the  tooth  space. 

Having  arranged  the  index-plate,  we  now  proceed  to  rough-cut  the 
gear.  We  cannot  finish  the  teeth  in  cutting  around  once,  because  the 
space  between  the  teeth  must  be  wider  at  H,  and  the  first  cutting  will 
not  give  this  result.  In  Fig.  629  the  blank  spaces  show  the  grooves 
made  in  the  first  cutting,  while  the  dotted  lines  show  the  spaces  as  they 
will  appear  when  finished. 

It  will  be  understood  that  both  the  teeth  and  the  spaces  are  taper- 
ing; and  having  taken  the  first  cut  around  the  gear  the  metal  left 
between  the  dotted  line  D  and  full  line  L  must  next  be  cut  away.  To 
effect  this  the  dividing  spindle  is  rotated  or  swiveled  slightly  on  its  axis. 
This  operation  moves  any  point  H,  on  the  greatest  diameter  of  the  gear, 
farther  than  F  on  the  small  diameter.  If  the  student  does  not  under- 
stand why  this  enables  us  to  cut  more  from  the  thick  end  of  the  tooth 
than  from  the  thin  end  it  may  be  made  clearer  by  the  following  reason- 
ing. It  is  evident  that  if  the  gear  be  rotated,  H  will  move  a  greater 
distance  than  F;  for  C,  which  is  a  prolongation  of  HF,  being  a  point 
on  the  axial  line  of  the  dividing-head  spindle,  does  not  move  at  all 
This  being  true,  any  point  between  H  and  C,  on  the  line  HFC,  must 
move  a  shorter  distance  than  H.  It  should  be  clear,  then,  that  the 
spaces  between  the  teeth  may  be  made  tapering  by  slightly  rotating 
the  gear  and  moving  it  laterally  in  the  opposite  direction.  This  being 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK  449 

repeated  on  each  side,  and  the  gear  fed  to  the  cutter  in  each  instance, 
the  space  will  be  made  tapering  symmetrically  with  respect  to  its  center 
line.  The  thickness  should  be  marked  off  on  one  or  two  teeth  as  a  guide 
to  cut  by. 

It  will  be  necessary  to  explain  why  the  gear  is  moved  laterally  when 
swiveling  for  a  taper.  It  is  found  that  when  the  gear  is  swiveled  suffi- 
ciently to  give  the  correct  taper  to  the  teeth  the  latter  would  be  cut 
too  thin  did  we  not  make  another  adjustment  to  offset  this.  This  adjust- 
ment consists  in  moving  the  gear  laterally  by  the  hand-wheel  /,  which 
moves  the  clamp-bed  (see  Fig.  546) .  This  tapering  process  can  be  best 


explained  by  considering  the  operation  of  cutting  a  miter-gear  of  some 
definite  size,  say  12-pitch,  40  teeth,  on  a  No.  1  B.  &  S.  miller.  The 
index-plate  used  for  this  gear  has  among  the  circles  one  circle  of  39  holes. 
To  thin  the  tooth  next  to  the  left  side  of  the  cutter  (looking  at  Fig.  630) 
the  index-crank  is  turned  in  the  direction  of  arrow  No.  1,  5  spaces  of 
the  39  circle.  This  turns  the  gear  toward  arrow  No.  3.  To  avoid  cut- 
ting too  much  off  the  tooth  the  gear  is  now  moved  laterally  .018" 
in  the  direction  of  arrow  No.  5.  As  stated,  this  movement  is 
effected  by  moving  the  hand-wheel  J,  Fig.  546.  With  this  new  posi- 
tion of  the  index-crank  for  a  starting-point,  the  teeth  may  now  be 
finished  on  one  side.  After  completing  one  side,  the  index-crank  is 
turned  10  spaces  (or  5  spaces  from  the  original  position)  toward  arrow 
No.  2,  and  the  clamp-bed  is  moved  to  take  the  gear  .036"  (or  .018" 
from  the  original  position)  toward  arrow  No.  6,  Fig.  630.  Dividing  the 
gear  from  this  new  position  of  the  index-crank,  we  proceed  to  finish 
the  opposite  sides  of  the  teeth. 


450  MACHINE-SHOP  TOOLS  AND  METHODS 

The  thickness  and  addendum  should  be  given  on  the  drawing  for 
each  end  of  the  tooth,  and  this  may  be  measured  by  a  gear-tooth  Vernier 
caliper  as  shown  at  Fig.  631.  In  the  absence  of  such  an  instrument 
the  gage  shown  in  Fig.  632  may  be  used. 

It  has  been  found  somewhat  difficult  to  convey  to  the  student  a 
clear  idea  of  the  last  part  of  bevel-gear  cutting.  It  may  be  well,  there- 
fore, to  repeat  the  instruction  for  tapering  the  teeth.  Thus,  to  take 
the  first  tapering  cut  we  move  the  index-crank  toward  arrow  No.  1,  5 
spaces  on  the  89  circle,  and  move  the  clamp-bed  .018"  toward  arrow 
No.  5.  To  trim  the  opposite  side  of  the  tooth  we  move  the  index-crank 
toward  arrow  No.  2,  10  spaces  from  last  position  and  move  the  clamp- 
bed  .036"  from  last  position  in  the  direction  of  arrow  No.  6 . 

It  is  important  to  observe  in  this  connection  that  in  adjusting  the 
gear  laterally  the  lost  motion  in  the  screw  must  be  kept  in  one  direction. 
Thus,  having  turned  the  hand- wheel  of  the  clamp-bed  through  an  arc 
which  moves  the  dial-pointer  .018"  to  the  left  of  zero,  in  moving  to  the 
opposite  side  it  would  not  answer  to  merely  move  it  .036"  backward.  This 
would  reverse  the  lost  motion;  and  while  the  hand- wheel  would  move 
through  an  arc  corresponding  to  .036",  the  clamp-bed  would  move  less. 
In  moving  to  the  opposite  side  of  zero  the  dial-pointer  should  be  turned 
backward  about  one  half  of  a  revolution  and  then  be  moved  forward 
and  stopped  .036"  short  of  the  previous  position.  By  this  method 
the  lost  motion  does  not  interfere  with  the  reading  on  the  dial,  be- 
cause, notwithstanding  the  hand-wheel  moves  in  opposite  directions, 
its  final  movements  are  in  one  and  the  same  direction  for  the  two 
opposite  adjustments  of  the  clamp-bed. 

It  should  be  explained  that  while  the  amount  of  the  lateral  and 
swivel  movements  for  tapering  the  teeth  of  one  particular  gear  are  here 
given,  these  adjustments  may  not  apply  to  a  different  gear.  In  prac- 
tice these  adjustments  are  found  by  trial  and  error,  and  when  thus 
found  the  operator  makes  memoranda  of  them,  and  thus  saves  doing 
the  work  again  for  duplicate  gears.  It  should  also  be  noted  that  in 
practice  the  first  or  parallel  cut  is  not  made  except  in  coarse  pitches, 
but  it  may  be  well  to  have  the  beginner  make  the  three  cuts. 

Common  Method  not  Theoretically  Correct.— The  tooth  of  a  bevel- 
gear  varies  in  curvature  between  the  thick  and  thin  end,  but  the  disk- 
cutter  will  not  make  such  curvature.  The  method  here  outlined,  though 
commonly  used  in  practice,  is,  for  the  above  reasons,  not  theoretically 
correct.  The  cutter  cannot  be  right  for  both  ends  of  the  tooth,  and 
the  usual  practice  is  to  select  a  cutter  of  correct  shape  for  the  thick 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          451 

end,  as  has  been  explained,  and  correct  the  remainder  of  the  tooth 
by  filing.  Some  prefer  to  use  a.  cutter  of  correct  shape  for  the  center 
of  the  tooth.  In  this  case  the  'thick  end  of  the  teeth  will  be  too  much 
rounded,  but  for  most  purposes  ^rie  gear  will  be  fairly  satisfactory  with- 
out any  filing. 

When  bevel-gears  are  to  run  at  a  very  high  speed,  or  have  very 
long  faces,  the  method  of  cutting  the  teeth  here  described  is  not  very 
satisfactory.  For  such  gears  there  are  machines  in  use  which  will  cut 
the  teeth  theoretically  correct,  but  the  process  is  slower  and  more  expen- 
sive than  the  one  above  explained. 

Cutting  Rack -teeth. — The  attachment  shown  in  Fig.  599  is  a  very 
satisfactory  device  for  cutting  racks  in  the  miller.  If  the  rack  is  not 
greater  than  about  8"  long  it  may  be  held  in  a  common  miller  vise,  but 
a  long  rack  is  best  held  in  a  special  fixture.  If  two  or  more  be  held  in 
the  vise  or  fixture  the  cut  may  be  made  through  all  of  them  in  one  opera- 
tion. The  depth  of  space  is  measured  in  connection  with  the  graduated 
dial,  the  same  as  in  cutting  the  spur-gear,  but  the  teeth  are  spaced  by 
an  entirely  different  method.  The  distance  between  the  centers  of  the 
teeth  is,  of  course,  the  circular  pitch,  and  when  the  diametral  pitch  only 
is  known,  the  circular  pitch  is  found  by  dividing  3.1416  by  the  diametral 

pitch.     Thus  the  circular  pitch  of  a  12-pitch  gear  equals     '          =.262". 

Now  having  a  graduated  dial  on  the  table-screw  it  is  a  very  simple  matter 
to  feed  the  table  by  hand  .262"  for  each  tooth,  the  rack  being  fed  to  the 
revolving  cutter  by  the  hand-wheel  which  moves  the  clamp-bed. 

When  large  numbers  of  racks  are  required  it  sometimes  pays  to 
purchase  a  special  rack-cutter.  Some  of  these  machines  are  so  con- 
structed that  a  number  of  cutters  may  be  strung  together  on  the  same 
arbor,  so  as  to  cut  as  many  teeth  in  one  operation  as  there  are  cutters. 
Now  if  there  are,  say,  6  racks  clamped  to  the  table,  then  six  times  as  many 
teeth  as  there  are  cutters  may  be  cut  in  one  operation. 

Direction  of  Rotation  of  Cutter. — Milling-machines  are  commonly 
equipped  with  both  forward  and  backing  belts,  and  the  beginner  needs 
to  be  informed  as  to  the  proper  relation  between  the  direction  of  table 
movement  and  cutter  rotation.  It  takes  but  little  experience  to  learn 
that,  with  rare  exceptions,  the  work  should  be  fed  against  the  front  or 
cutting  faces  of  the  teeth,  as  at  A ,  Fig.  633 .  If  the  feed  be  ' ' with  the  teeth/ 7 
as  at  B,  the  work  is  likely  to  be  pulled  forward  an  amount  equal  to  the 
freedom  or  backlash  in  the  screw  or  rack.  This  causes  the  cutter  to 
dio;  in,  and  sometimes  breaks  the  teeth. 


452 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  best  authorities  say  that  the  cutter  will  remain  sharp  much  longer 
when  the  work  is  fed  as  at  A.  This  is  certainly  true  when  surfacing  a 
rough  casting.  The  reason  is  that  after  the  cutter  has  entered  the  work 
it  no  longer  attacks  the  hard  scale  from  above,  but  breaks  it  off  from 


FIG.  633. 

below.  In  the  latter  case  the  scale  has  but  little  support  and  yields 
with  light  pressure. 

The  reasons  given  for  running  the  cutter  with  the  feed  seem  to  have 
but  little  weight.  There  is  one  case,  nowever,  in  which  it  may  be  ad- 
vantageous to  run  the  cutter  in  this  way.  It  is  that  of  milling  a  deep 
slot  with  a  cutter,  say,  l/i§  to  3/16  inch  thick.  In  this  work  the  cutter 
is  very  likely  to  make  the  slot  crooked.  Better  results  may  possibly  be 
obtained  in  such  work  with  the  cutter  running  with  the  feed  as  at  B. 
In  the  latter  case  the  table  gib-screws  should  be  somewhat  tighter  than 
usual.  The  same  precaution  should  be  used  when  the  cutter  is  cutting 
both  top  and  bottom  at  the  same  time,  as  in  Fig.  580.  Some  wrorkmen 
counterweight  the  table  in  such  cases. 

It  should  be  observed  that  the  common  size  cutters  are  held  on  the 
arbors  by  friction  between  the  cutters  and  the  collars,  these  being  bound 
together  by  the  nut  on  the  outer  end  of  the  arbor.  Now,  as  the  miller- 
spindle  runs  in  both  directions,  some  of  the  arbors  must  have  right-hand 


MILLING-MACHINES  AND  MILLING-MACHINE  WORK          453 

thread  and  some  left-hand  thread.  When  the  cutter  runs  clockwise, 
the  arbor  with  left-hand  thread  should  be  used  and  vice  versa. 

Speed  and  Feed  of  Milling-caters. — In  some  of  the  examples  of  mil- 
ling the  speed,  feed  and  (iepth  of  cut  have  been  given.  These  rates  apply 
to  particular  cases  and  are  supposed  to  represent  rapid  work.  It  is 
difficult  to  give  a  general  rule.  The  depth  of  cut,  character  of  material, 
number  of  teeth  in  the  cutter,  etc..  are  factors  which  must  be  considered. 
The  Brown  &  Sharpe  Manufacturing  Company,  in  their  book  entitled 
" Construction  and  Use  of  Milling-Machines,"  after  acknowledging  the 
difficulties  of  the  problem,  say:  "The  average  speed  on  wrought  iron 
and  annealed  steel  is  perhaps  40'  a  minute.  .  .  .  The  feed  of  the  work 
for  this  surface  speed  of  the  cutter  can  be  about  1 1/2"  a  minute  and  the 
depth  of  cut,  say,  Vie".  In  cast  iron  a  cutter  can  have  a  surface 
speed  of  about  50'  a  minute,  while  the  feed  is  I1/ 2"  a  minute  and  the 
cut  3/i6"  deep,  and  in  tough  brass  the  speed  may  be  80',  the  feed  as 
before,  and  the  chip  3/32"«" 

But  as  showing  how  the  speed  may  be  increased  under  favorable 
conditions  the  same  authority  cites  cases  in  which  cutters  have  been  run 
in  their  own  works  at  125'  per  minute,  while  the  work  was  fed  more  than 
8"  a  minute.  In  the  cases  referred  to  the  work  consisted  of  short  pieces 
of  annealed  cast  iron  and  the  cut  was  only  l/&"  deep. 

In  the  book  above  mentioned  an  English  authority  is  quoted  as 
proposing  the  following  speeds  and  feeds  for  cutters  6"  diameter  and 
upwards : 

Steel 36  feet  per  minute  with  a  feed  of  1/2//  per  minute 

Wrought  iron.  ..   48    "     il        li         H     "    "     "      1"  " 

Cast  iron 60    "     "        "         "    "    ll    "      1"  " 

Brass 120    "     il        "         ll    "    "    "      1"  "        " 

The  same  book  quotes  another  authority  to  the  effect  that  in  milling 
wrought  iron  with  a  cut  I"  deep  (note  that  this  is  quite  different  from 
mere  surface  milling)  a  surface  speed  of  36  to  40  feet  was  all  that  was 
practicable. 

The  speeds  above  given  were  doubtless  meant  to  be  used  in  connec- 
tion with  ordinary  tool-steel  cutters.  With  high-speed  steel  greater 
speeds  should  be  practicable.  In  this  connection  read  pages  123  and  173 
on  high-speed  steels. 

The  following  is  taken  from  a  card  of  instructions  written  by  the 
author  and  posted  near  the  milling-machine  at  the  Michigan  Agricul- 
tural College: 


454  MACHINE-SHOP  TOOLS  AND  METHODS 


INSTRUCTIONS   FOR   USE   OF   ARBORS   ON   THE   MILLING-MACHINE 

Before  inserting  the  cutter-arbor  see  that  both  the  arbor  and  socket 
in  the  end  of  the  spindle  are  clean.  The  spindle  socket  may  be  cleaned 
by  wrapping  waste  around  a  stick  and  swabbing  out  the  socket  while 
the  spindle  is  revolving.  Dirt,  or  hammer-marks  on  the  arbor  will  cause 
it  to  revolve  eccentrically. 

The  same  precautions  are  necessary  in  connection  with  the  slip- 
collars  on  the  arbor.  The  smallest  speck  of  grit  between  these  collars 
will  cause  the  arbor  to  be  bent  when  the  clamping-nut  is  tightened. 
Therefore  these  collars  must  also  be  carefully  cleaned.  The  collars 
furnished  with  the  arbor  are  made  of  tool  steel  hardened  and  ground , 
and  cast-iron  collars  must  not  be  used.  The  objection  to  the  cast-iron 
collar  is  that  it  is  easily  bruised  in  use.  The  slightest  lump  made  on 
the  face  of  the  collar  in  this  manner  will  have  the  same  effect  as  a  particle 
of  grit,  i.e.,  it  will  cause  the  arbor  to  be  sprung  when  the  clamping-nut 
is  tightened. 

Both  the  cutter-arbor*  and  the  arbor  used  in  dividing-head  spindle 
must  be  driven  in  tightly.  Use  the  rawhide  mallet,  or  the  hammer  and 
a  block  of  hard  wood.  When  not  tightly  secured  the  arbors  are  likely 
to  get  loose  and  spoil  the  work. 

If  the  arbor  which  holds  the  work  be  used  between  centers,  the  set- 
screw  in  the  driver  on  dividing-head  spindle  must  be  closely  adjusted 
against  the  tail  of  the  dog  on  the  arbor;  otherwise  there  will  be  an  error 
in  the  dividing.  If  the  arbor  be  held  in  the  socket  of  the  dividing-head 
spindle,  both  socket  and  arbor  must  be  carefully  cleaned  according  to 
instructions  respecting  the  main  spindle  socket. 

A  gear  or  other  work  held  on  an  arbor  in  the  dividing-head  spindle 
should  be  placed  as  close  to  the  spindle  as  practicable  to  avoid  deflection. 

*So  far  as  the  cutter-arbor  is  concerned,  this  paragraph  was  meant  to  apply 
more  particularly  to  a  miller  which  lacked  the  overhanging  arm. 


CHAPTER   XXVII 
SPECIAL  GEAR-MACHINES 

The   Gould   and  Eberhardt  Automatic  Gear-cutter. — The  adapta- 
tion of  the  universal  miller  to  gear-cutting  has  been  briefly  described. 


FIG.  634. 

An  automatic  gear-cutter  used  for  gear-cutting  only  is  shown  hi  Figs. 
634  and  635.  This  machine  cuts  spur-,  bevel-,  skew-,  and  face-gears. 
As  a  rotary-disk  cutter  is  employed,  the  machine  might  be  considered 
as  a  special  form  of  miller.  However,  there  are  important  differences 

455 


456  MACHINE-SHOP  TOOLS  AND   METHODS 

in  the  construction  and  operation  of  the  two  machines.  In  the  auto- 
matic gear-cutter,  in  addition  to  the  rotary  motion,  the  cutter  is  given 
a  traversing  motion.  In  other  words,  the  cutter  is  fed  to  the  gear  instead 
of  the  gear  being  fed  to  the  cutter.  The  indexing  system  is  also  dif- 
ferent, as  will  be  presently  shown. 

Referring  to  Fig.  634,  the  driving-pulley  A  is  mounted  on  a  sleeve- 
bearing,  so  that  the  pulley-shaft  is  relieved  from  the  side  strain  due  to 
the  pull  of  the  belt.  By  means  of  a  pair  of  miter-gears  motion  is  com- 
municated from  the  shaft  of  A  to  the  side-shaft  B.  The  shaft  0  seen 
just  above  B  is  driven  from  the  latter  by  spur-gears.  The  end  of  the 
cutter-spindle  is  seen  projecting  at  E.  This  spindle  is  driven  by  worm- 
gearing,  the  worm  being  splined  to  shaft  0.  At  C  are  shown  a  pair  of 
spur-gears  which  may  be  changed  for  other  gears  having  different  ratios. 
These  are  the  "change-gears, "  by  which  the  velocity  of  the  cutter-spindle 
is  varied.  The  cutter-slide  is  fed  by  screw  F.  This  screw  is  operated 
by  gears  D,  which  may  be  changed  to  give  different  rates  of  feed. 

Enclosed  within  a  gear-guard  at  P  is  the  dividing  worm-wheel. 
This  worm-wheel  serves  the  same  purpose  as  the  worm-wheel  in  the 
dividing-head  in  the  milling-machine.  P  is  operated  by  a  worm  on  K, 
which  in  turn  is  driven  by  the  vertical  shaft  T  and  spur-gearing.  The 
gear  to  be  cut  is  held  on  the  arbor  H,  the  outer  end  of  which  is  sup- 
ported as  shown.  The  arbor  and  gear  are  driven  by  driving  fixtures 
secured  to  the  face-plate  near  the  right  of  H.  In  cutting  a  gear  having 
arms  or  spokes,  one  of  the  spokes  engages  with  the  U-shaped  carrier  shown 
at  7.  The  gear,  and  with  it  the  dividing  worm-wheel,  etc.,  is  raised  by 
a  screw  and  bevel-gear  mechanism  shown  at  the  top  of  the  machine, 
this  being  operated  by  the  crank  J.  The  crank-shaft  is  provided  with 
a  dial  graduated  to  thousandths  of  an  inch,  by  which  the  depth  of  cut 
is  measured. 

In  cutting  bevel-gears  the  cutter-slide  is  elevated  to  the  required 
angle  by  means  of  a  crank  applied  at  M.  (See  Fig.  635.)  As  shown, 
this  crank  turns  a  worm  operating  a  cross-shaft  by  means  of  a  worm- 
wheel.  On  this  cross-shaft  are  two  pinions  meshing  with  the  slotted 
quadrant  K  1.  When  raised  to  the  required  angle  the  quadrant  is 
locked  by  means  of  a  nut  seen  to  the  left  of  the  worm-wheel.  In  cut- 
ting bevel-gears  in  this  machine  at  least  two  cuts  (sometimes  three) 
must  be  taken,  one  on  each  side  of  the  tooth.  For  this  purpose  the 
cutter-slide  is  arranged  to  swivel  a  slight  amount  to  the  right  and  left 
of  the  center  line.  When  three  cuts  are  taken,  one  is  a  central  cut. 
This  central  cut  is  made  for  the  same  purpose  that  a  central  cut  is  some- 


SPECIAL  GEAR-MACHINES 


457 


times  made  in  cutting  a  bevel-gear  in  the  miller.  When  the  cutter- 
slide  is  raised  and  swiveled  it  carries  the  left  section  of  shaft  B  (Fig.  634) 
with  it.  To  provide  for  thus  raising  shaft  B,  it  is  connected  to  a  short 
shaft  at  its  right  end  by  a-universa$joint. 


FIG.  635. 

The  pressure  of  the  cut  in  cutting  both  spur-  and  bevel-gears  is 
sustained  by  the  adjustable  support  R. 

The  Indexing  Mechanism. — The  change-gears  shown  at  Q  in  Fig.  635 
are  connected  by  shafts  and  gearing  to  the  indexing  worm-wheel.  In 
the  casing  behind  this  gearing  is  a  locking  device  which  makes  one 
revolution  for  each  spacing  of  the  gear  being  cut,  regardless  of  the  num- 
ber of  teeth  in  the  latter.  To  give  this  locking  device  one  revolution, 
the  gears  at  Q  are  changed  for  each  different  number  of  teeth  in  the 
gear  being  cut.  The  locking  device  is  made  with  extreme  accuracy t 
and  its  operation  is  such  as  to  eliminate  all  errors  due  to  the  wear  of 
change-gears  and  connecting-shafts. 


458  MACHINE-SHOP  TOOLS  AND  METHODS 

Construction  of  the  Dividing  Worm-wheel. — When  a  very  accurate 
worm-wheel  is  required,  it  is  customary  to  make  the  rim  in  two  separate 
rings,  and  bolt  these  together.  The  object  of  this  construction  is  to 
avoid  possible  errors  in  hobbing  the  teeth.  The  correction  is  made 
as  follows:  Having  hobbed  the  worm-wheel  once  around,  before  the 
final  cut  is  taken  the  removable  section  is  turned  one-half  revolution 
and  the  hobbing  is  repeated.  This  divides  up  minute  errors  which 
may  occur  in  the  first  hobbing.  In  making  the  dividing-wheel  of  the 
machine  under  consideration  this  shifting  and  re-hobbing  is  repeated 
a  number  of  times,  thus  further  eliminating  the  possibility  of  error. 

With  the  exceptions  noted  above  in  the  description,  the  cutting  of 
gears  in  the  automatic  gear-cutter  does  not  differ  greatly  from  the 
method  used  in  the  miller.  It  will  be  understood,  however,  that  as  the 
indexing,  feeding  back  and  forth  of  the  cutter,  etc.,  are  all  automatic, 
the  chances  of  error  are  reduced  to  a  minimum,  and  one  workman  can 
operate  several  machines.  Having  started  the  cutting  of  a  gear,  the 
machine  automatically  makes  all  the  movements  necessary  to  complete 
the  gear,  and  when  completed  a  gong  is  automatically  sounded,  notifying 
the  workman  that  the  gear  is  ready  to  be  removed. 

Gang-cutters. — The  manufacturers  of  the  machine  just  described 
make  cutters  which  may  be  used  in  gangs  for  cutting  gears  having  more 
than  30  teeth.  The  object  is  the  same  as  in  the  case  of  cutting  rack- 
teeth  with  gang-cutters.  From  2  to  12  cutters,  according  to  the  num- 
ber of  teeth  in  the  gear,  may  be  used.  As  these  cutters  must  have 
proper  contact  on  the  periphery  of  the  gear-blank,  it  is  evident  that 
the  cutters  will  be  of  varying  diameter.  The  hub  thickness  or  hub 
length  of  the  cutters  must  be  gaged  very  accurately  to  bring  the  cutters 
the  right  distance  apart.  Special  precautions  are  required  in  using  these 
cutters,  and  the  gear-blanks  must  be  quite  accurate  as  to  diameter;  but 
when  a  large  number  of  gears  of  one  kind  are  required,  the  great  saving 
in  time  fully  justifies  the  extra  care  required. 

Fellows  Gear-shaper. — Theoretically,  cut  gears  should  require  a 
different  cutter  for  every  different  number  of  teeth  in  the  gears.  There- 
fore cutters  made  on  the  principle  of  the  set  of  eight  involute  cutters 
previously  referred  to,  while  sufficiently  correct  for  all  ordinary  pur- 
poses, cannot  be  absolutely  right.  Where  greater  accuracy  is  required 
the  manufacturers  of  these  cutters  furnish  them  in  sets  having  a  greater 
number  of  cutters  to  each  set,  and  they  will  also  make  special  cutters  to 
order.  However,  the  machine  shown  in  Fig.  636  is  designed  to  regularly 
make  gears  of  theoretically  correct  tooth  outline. 


SPECIAL  GEAR-MACHINES 


459 


Imagine  a  gear-blank  of  some  plastic  material  held  upon  an  arbor 
and  a  complete  gear  secured  to  'another  arbor  parallel  with  the  first. 
Now,  let  the  gear  be  pressed  int^  the  blank  to  the  correct  tooth-depth 
and  caused  to  make  one  complete  revolution.  Assuming  that  there 
is  perfect  rolling  contact  between  the  pitch-line  of  the  blank  and  that 


FIG.  636. 

of  the  gear,  the  latter  will  generate  on  the  blank,  teeth  of  theoretically 
correct  shape.  This  is  the  principle  upon  which  gear-teeth  are  gener- 
ated in  the  above-mentioned  machine.  The  actual  operation,  how- 
ever, is  different  in  that,  in  addition  to  the  revolving  motion  of  gear 
and  cutter,  the  latter  is  given  also  a  reciprocating  motion  like  that  of 
the  slotting-machine  ram.  The  principle  of  the  machine  may  be  further 
explained  by  the  consideration  of  the  method  of  making  the  cutters. 
In  Fig.  637  will  be  seen  an  emery-wheel  having  one  straight  face  at 
right  angles  to  the  wheel  axis.  The  means  for  dressing  the  side  of  the 
emery-wheel  is  such  as  to  insure  a  high  degree  of  accuracy.  In  con- 


460 


MACHINE-SHOP  TOOLS  AND  METHODS 


nection  with  the  emery-wheel  is  shown  also  a  small  gear.  This  gear 
is  in  reality  a  steel  cutter  which  has  been  roughed  out  to  the  approxi- 
mate shape  and  hardened.  The  diagram  is  designed  to  show  a  method 
of  presenting  the  cutter  to  the  revolving  emery-wheel  in  a  manner  to 
grind  the  teeth  of  the  cutter  to  the  exact  shape.  The  sides  of  a  theo- 
retical involute  rack-tooth  are  straight,  the  angle  of  each  side  being 


Ornery  Wheel 


Cutter 


FIG.  637. 


75 1/2°  with  the  pitch-line.  The  straight  face  of  the  emery-wheel,  being 
placed  at  the  required  angle  with  the  path  of  the  cutter,  is  intended 
to  represent  one  side  of  such  a  rack-tooth. 

The  cutter  is  rolled  past  the  revolving  emery-wheel  at  the  required 
angle  in  true  rack  and  pinion  motion,  and  for  each  passage  of  the  cutter 
one  side  of  one  tooth  is  formed.  This  is  repeated  for  each  tooth,  when 
the  cutter  is  reversed  and  the  same  process  is  followed  for  the  opposite 


SPECIAL  GEAR-MACHINES  461 

side.     Fig.  638  shows  one  of  the  cutters  and  one  of  the  methods  for 
holding  it.     It  will  be  seen  that  the  cutter  has  the  proper  clearance. 

In  Fig.  639  is  shown  a  cutter  in  connection  with  a  partially  developed 
gear.     This   figure   illustrates   the   method   of   starting   the   cut.     The 


CUTTER 

FIG.  639 

machine  being  set  in  motion,  the  cutter  is  gradually  fed  to  the  full  depth" 
in  the  blank,  when  both  blank  and  cutter  begin  to  revolve  just  as  though 
they  were  two  gears.  The  reciprocating  motion  is,  of  course,  main- 
tained during  the  rotary  motion,  the  result  being  that  in  one  revolution 
the  blank  becomes  a  finished  gear.  To  prevent  the  rubbing  and  wearing 
action  of  the  cutter  on  the  gear-teeth,  during  the  return-stroke  the 
cutter  is  moved  outward  slightly.  By  a  similar  mechanism  it  is  brought 
back  to  its  cutting  position  at  the  beginning  of  the  downward  stroke. 
The  names  of  the  various  parts  of  the  machine  are  given  in  connection 
with  Fig.  640. 

It  is  important  to  observe  that  in  this  system  of  gear-cutting  only 
one  cutter  is  needed  for  each  pitch.  This  cutter  cuts  both  external 
and  internal  gears.  Fig.  641  shows  the  two  gears  in  one  casting  and 
the  cutter  in  position  for  cutting  an  internal  gear.  The  dotted  lines 
on  the  opposite  side  show  the  cutter  in  correct  position  for  shaping 
the  tooth  of  an  external  gear. 

The  Gleason  Gear-planer. — As  has  been  stated,  the  method  of  cutting 
bevel-gears  in  a  miller  is  not  satisfactory  for  gear-teeth  having  extra 
long  faces.  The  longer  the  face  the  greater  is  the  variation  from  the 
theoretical  shape. 


462 


MACHINE-SHOP   TOOLS  AND  METHODS 


If  we  stretch  a  fine  thread  along  the  side  of  a  bevel-gear  tooth  from 
the  apex  of  the  pitch-cone  to  the  outer  curved  edge  of  the  tooth,  the 
thread  will  follow  the  side  of  the  tooth  throughout  the  length  of  the 
latter.  If  the  outer  end  of  the  thread  be  moved  to  another  position, 


Adjustment  for  position 

of  Cutter  Rotate  Cutter' 


Driving 

Crank 


Pilot  Wheel 


Locking  Pin 


Apron  Lever 


Detachable 
Levrf 


Worm 

Adjust  nienl 


Work  Support 
Cutter  Slide  - 
Cutter 

Work  Arbor 

. — - 
Chip  Pan 

Apron 


Lower  Index 
Feed  Trip 
Chance  Gears 


FIG.  640. 

the  inner  end  being  held  as  before,  the  thread  will  still  remain  in  contact 
with  the  side  of  the  tooth.  The  principle  of  a  bevel-gear  tooth,  as 
distinguished  from  the  spur-gear  tooth,  may,  therefore,  be  represented 
by  an  infinite  number  of  straight  lines  extending  from  the  outer  curved 
outlines  of  the  tooth  to  the  apex  of  the  pitch-cone. 

The  Gleason  bevel-gear  machine  is  simply  a  system  of  mechanism 
designed  to  give  practical  effect  to  this  principle  in  planing  gear-teeth. 
Figs  642  and  643  show  respectively  perspective  and  outline  views  of 


SPECIAL  GEAR-MACHINES 


463 


the  Gleason  machines.  The  construction  of  Fig.  643  is  slightly  dif- 
ferent from  that  of  the  machine^  in  the  perspective  view,  but  it  never- 
theless helps  to  explain  the  princigj^  of  the  latter.  The  formers,  which 
are  the  main  elements  to"  give  effect  to  the  above  principle,  are  clearly 


Work 


shown  on  the  front  of  the  machine  in  the  perspective  view.  As  seen 
in  Fig.  643,  the  gear  is  held  on  the  head-spindle  at  G,  and  before  the 
cutting  is  begun  the  head  must  be  moved  to  bring  the  apex  of  the  gear 
to  the  center  of  the  machine.  To  facilitate  this  work  a  gage  for  the 
purpose  is  furnished  with  each  machine.  In  this  machine  a  single- 
point  tool  is  caused  to  reciprocate  in  very  much  the  same  way  as  a 
shaper-tool,  the  guide  for  the  tool  being  pivoted  at  its  inner  end  in  a 
universal  joint,  and  caused  to  follow  the  curved  former  at  its  outer  end. 
The  manufacturers  of  this  machine  explain  the  movements  of  the  cutting- 
tool  as  follows:  "The  arm  on  which  the  tool-holder  travels  is  rotated 
around  the  center  of  the  machine  in  a  horizontal  plane.  Besides  this 
horizontal  movement  of  the  arm,  it  is  hinged  at  the  center  of  the 
machine  so  as  to  give  a  vertical  movement  as  it  is  fed  over  the  former, 
so  that  the  tool  travels  always  at  the  correct  angle  of  the  gear  from 


464 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  top  of  the  tooth  to  the  root,  and  the  tooth,  therefore,  has  the  perfect 
reducing  cut,  the  small  end  being  in  proportion  to  the  large  end." 

The  tooth-curve  of  the  former  is  produced  by  a  machine  designed 
especially  for  this  purpose,  and  there  is  practically  no  wear  on  the  former 
because  it  is  used  in  connection  with  a  roller. 


FIG.  642. 

During  the  time  that  the  tool  is  cutting  the  gear  is  stationary,  the 
same  as  in  a  milling-machine.  The  first  operation  is  to  cut  a  central 
groove  for  each  tooth.  This  is  accomplished  by  the  roughing  or  "  stock- 
ing" cutter  shown  in  Fig.  644.  During  the  second  operation  the  upper- 
cut  tool  shown  in  Fig.  645  planes  one  side  of  each  tooth.  This  tool 
is  removed  and  the  under-cut  tool  of  Fig.  646  is  used  to  finish  the  oppo- 
site side  of  each  tooth.  Thus  it  requires  three  tools  and  three  revo- 


SPECIAL  GEAR-MACHINES 


465 


lutions  of  the  blank  to  complete  the  gear.     The  gear  is  indexed  for 
each  tooth  after  the  completion  pf  "the  work  of  each  tool  upon  the  tooth. 


CRANK  SHAFT 


FIG.  643. 

The  slide  which  carries  the  tool-holder  is  driven  from  the  cone 
through  triple  gears,  and  has  a  Whitworth  quick-return.  The  feed  is 
worm-driven  and  positive.  These  machines  are  made  for  bevel-gears 
only,  and  with  each  machine  a  number  of  formers  sufficient  for  all  the 
gears  within  the  capacity  of  the  machine  is  furnished.  The  same  com- 
pany makes  also  spwr-gear  planers. 


466 


MACHINE-SHOP  TOOLS  AND  METHODS 


In  referring  to  a  few  of  the  leading  gear-cutting  machines  the  Bil- 
gram  bevel-gear  planer  should  not  be  omitted.  This  machine  cuts 
bevel-gears  having  either  long  or  short  faces  theoretically  correct. 


STOCKING  CUT  TOOL 


FIG.  644. 


t'°PER  CUT  TOCl 

FIG.  645. 


UNDER  CUT  TOOL 

FIG.  646. 


The  use  of  bevel-gears  on  bicycles  stimulated  the  design  of  special 
machines  for  cutting  the  gears.  Most  of  these  machines  have  a  narrow 
range,  being  designed  for  small  gears  only. 


CHAPTER  XXVIII 
GRINDING  MACHINES  AND  METHODS 

AN  old-time  machinist  entering  a  modern  machine-shop  will  note 
many  changes  and  improvements.  Among  these  he  will  find  that  his 
old  familiar  friend,  the  grindstone,  to  which  water  was  fed  by  a  shingle 
or  stick  and  which  filled  the  shop  with  dust  every  time  it  was  " trued 
up,"  has  been  superseded  by  the  more  pretentious  emery-grinder, 
mounted  in  a  trim  box-frame  and  having  automatic  water-supply  and 
dustless  truing-roll.  There  are  still  those  who  believe  in  the  grind- 
stone. These  contend  that  had  the  grindstone  received  as  much  atten- 
tion and  had  it  been  given  as  good  a  chance  generally  as  the  emery- 
wheel,  it  would  still  be  a  strong  rival  of  the  latter.  Nevertheless,  it 
is  generally  conceded  that  the  emery-stone  has  come  to  stay,  and  those 
who  regret  the  change  are  few  and  far  between. 

Methods  of  Measuring  and  Designating  Abrasive  Materials. — Emery, 
corundum,  and  carborundum  are  the  principal  materials  used  for  grind- 
ing purposes.  These  materials  are  not  sufficiently  different  to  warrant 
a  detailed  description  within  the  space  here  available.  In  the  making 
of  an  emery-wheel  the  abrasive  material  is  mixed  with  some  kind  of 
cementing-material,  such  as  glue,  rubber,  etc.,  which  holds  the  wheel 
in  form.  Emery  and  other  abrasive  wheels  are  designated  with  respect 
to  the  size  of  the  grain  by  numbers.  These  vary  between  6  and  220, 
the  coarser  materials  taking  the  lower  numbers.  The  coarsest  and 
finest  numbers  are  very  seldom  used  for  manufacturing  purposes.  The 
sizes  most  employed  vary  from  16  to  150. 

The  various  sizes  of  emery  and  corundum  are  measured  in  a  sieve, 
and  the  number  of  the  abrasive  material  indicates  the  number  of  the 
meshes  per  square  inch  in  the  sieve.  Thus  No.  20  emery  means  that 
the  material  will  pass  through  a  sieve  having  20  meshes  per  square  inch. 

The  grade  of  an  emery-  or  corundum-wheel  is  the  measure  of  the 
resistance  of  its  outer  surface  to  crumbling.  A  wheel  of  which  the 
particles  are  easily  broken  down  or  separated  is  said  to  be  soft;  while 

467 


468 


MACHINE-SHOP  TOOLS  AND   METHODS 


one  which  does  not  easily  yield  under  pressure  of  the  work  is  said  to 
be  hard.  The  different  grades  or  degrees  of  hardness  are  indicated 
by  the  letters  of  the  alphabet.  Thus  A  is  the  softest  and  Z  the  hardest. 
For  all-round  purposes  the  medium-hard  wheel,  indicated  by  the  letter  M, 
is  the  one  commonly  used.  Mr.  C.  H.  Norton  recommends  for  grind- 
ing soft  steel  " grade  L  wheel,  No.  24  combination."* 

Grinders  for  Lathe-  and  Planer-tools. — A  good  example  of  the  modern 
wet  emery-grinder  for  general  tool-grinding  is  shown  in  Fig.  647.    The 


FIG   647. 


water-supply  in  this  machine  is  regulated  by  a  hand-wheel,  one  or  two 
turns  of  which  start  or  stop  the  supply.  It  is  well  distributed  over 
the  grinding  surface  and  a  guard  is  furnished  which  protects  the  sur- 

*  Two  or  more  numbers  mixed  together  give  a  "combination." 


GRINDING  MACHINES  AND  METHODS 


469 


rounding  machinery  from  the  spray  of  water  when  the  machine  is  not 
in  use.  Mounted  within  convenient  reach  above  the  rest  is  the  truing- 
roll,  which  can  be  applied  by  a  few  turns  of  a  knob.  To  get  the  best 
results  the  wheel  should  be  kept  true,  and  to  avoid  danger  from  the 
tool  catching  between  the  emery-wheel  and  rest,  the  latter  should  be 
moved  up  to  the  wheel  as  often  as  the  wheel  wears  an  appreciable 
amount.  It  should  be  kept  so  close  as  to  barely  clear  the  wheel. 

The  novice  should  be  informed  that  the  water  serves  an  important 
purpose,  and  that  unless  freely  used  it  would  be  necessary  to  spend 
considerable  time  in  the  forge-shop  retempering  the  tools. 

In  grinding  tools  in  connection  with  the  above-mentioned  machine, 
the  tool  is  held  in  the  hand  and  ground  according  to  the  judgment  and 


FIG.  648. 

skill  of  the  workman.  However,  there  are  on  the  market  machines  in 
which  the  tool  is  held  by  a  kind  of  tool-post  and  fed  to  the  wheel  by  a 
screw  or  other  mechanical  means.  These  machines  are  so  constructed 
that  any  number  of  tools  may  be  ground  to  the  same  angles,  the  tool- 


470  MACHINE-SHOP  TOOLS  AND  METHODS 

swiveling  devices  being  graduated,  and  a  table  giving  the  angles  for 
the  various  tools  being  furnished  with  the  machine. 

Emery-,  corundum-,  and  carborundum-wheels  mounted  on  simple 
frames  are  very  extensively  used  for  grinding  rough  castings  and  forg- 
ings  in  various  lines  of  manufacturing.  Fig.  648  shows  a  machine  of 
this  character.  These  machines  are  made  in  all  sizes  to  suit  a  variety 
of  purposes.  A  small  machine  of  this  same  general  design  is  some- 


PIG.  649. 

times  used  for  grinding  lathe-  and  planer-tools.  When  these  machines 
have  no  water-supply,  it  requires  some  care  to  avoid  burning  the  point 
of  the  tool.  Most  mechanics  keep  a  small  pail  of  water  near  the  grinder 
and  dip  the  tool  in  the  water  every  few  seconds. 

The  grinding  of  reamers,  milling-cutters,  etc.,  requires  different 
manipulations  from  that  of  ordinary  tool-grinding.  Fig.  649  shows  a 
machine  adapted  to  the  former  class  of  work.  There  are  special  machines 
designed  for  grinding  twist-drills  exclusively,  but  the  illustration  shows 


GRINDING  MACHINES  AND  METHODS 


471 


that  twist-drills  are  included  in  the  list  of  tools  that  may  be  ground 
on  this  machine.  For  this  purpose  and  for  some  other  purposes,  attach- 
ments to  the  machine  proper  are  furnished.  A  twist-drill  is  shown  in 
the  fixture  at  the  left  in--position*ibr  being  ground.  The  device  is  pro- 
vided with  adjustment  for  grinding  different  diameters  of  drills  and 
for  giving  the  drills  different  degrees  of  clearance. 

On  the  right  of  the  machine  is  seen  a  reamer  held  between  centers 
in  position  for  grinding,  a  small  emery-wheel  being  shown  just  above 
the  reamer.  To  grind  a  reamer  like  that  of  the  illustration,  the  reamer 


1. 

V         ~ 

FIG.  650. 

is  first  adjusted  in  correct  relation  with  the  wheel  to  give  the  required 
clearance.  The  finger-guide  seen  just  under  the  spindle  is  next  placed 
in  contact  with  the  front  of  one  cutting-edge,  and  the  reamer,  while 
being  moved  along  under  the  wheel,  is  held  against  the  guide.  Having 
ground  the  clearance  on  one  of  the  cutting-edges,  the  reamer  by  means  of 
the  slide  is  moved  beyond  the  guide  and  rotated  to  bring  the  next  cutting- 
edge  in  proper  relation  with  the  wheel  and  guide  and  so  ground,  this 
being  repeated  until  the  work  is  complete.  The  methods  of  grinding 
taper-reamers,  milling-cutters,  etc.,  are  indicated  in  Figs.  650  to  652. 

The  Universal  Grinder. — Fig.  653  shows  a  perspective  view  of  the 
No.  1  B.  &  S.  Universal  grinder,  and  Figs.  654  and  655  show  sectional 
views  of  the  spindle-boxes  and  head-stock  respectively.  Plain  grinders, 
which  are  used  for  heavier  work,  differ  from  the  universal  grinder  in 


472 


MACHINE-SHOP  TOOLS  AND  METHODS 


FIG.  651. 


FIG    652 


GRINDING  MACHINES  AND  METHODS  473 

being  heavier  and  in  having  fewer  adjustments  and  attachments. 
Fig.  656  shows  a  Landis  plain  grinder  and  some  of  its  accessories.  The 
universal  grinder  is  designed  t  for  quite  a  different  purpose  from  that 
of  the  common  tool-grinder.  3Jie  former  is  used  for  grinding  cylin- 


drical surfaces  more  accurately  than  it  is  possible  to  turn  them  in 
a  lathe.  A  shaft- journal,  which  is  required  to  run,  say  4000  R.P.M., 
if  turned  in  the  lathe  in  the  ordinary  manner,  would,  because  of  the 
minute  imperfections  in  the  lathe  work,  be  likely  to  heat.  If  finished 
in  the  grinder  it  would  run  without  heating. 


474 


MACHINE-SHOP  TOOLS  AND  METHODS 


Referring  to  Fig.  65£,  B  is  the  bed,  T  the  sliding  table,  T  1  the 
swivel  table,  H  the  head-stock,  T2  the  tail-stock,  E  the  emery-wheel,  P 
the  pulley  which  drives  the  emery-wheel,  and  P  1  and  P  2  the  pulleys 
which  drive  the  work.  The  work  is  either  held  between  the  centers  in 


head-stock  and  tail-stock  and  driven  by  a  dog,  or  it  is  carried  by  a 
chuck.  Generally  when  the  work  is  driven  by  a  dog  the  head-stock 
spindle  does  not  revolve,  but  the  pulley  P 1,  which  turns  freely 
on  the  spindle,  drives  the  work  by  contact  of  the  dog  with  the  pins 


GRINDING  MACHINES  AND  METHODS 


475 


projecting  from  the  pulley.  As  in  this  arrangement  neither  of  the 
centers  revolves,  errors  due.  to  an  eccentrically  revolving  head- 
center  are  impossible.  When1  the  work  is  carried  in  a  chuck,  pulley  P  1 
is  taken  off  and  the  ckuck  screwed  on  instead.  In  this  case  the  spindle 
is  driven  by  pulley  P2,  which  is  tight  on  the  spindle. 

The  emery-wheel  E  is  fed  to  the  work  by  means  of  the  hand-wheel 
H  2.  At  the  back  of  this  hand-wheel  is  a  graduated  ratchet-disk  by 
which  the  depth  of  cut  is  measured.  The  machine  is  provided  with 
power  cross-feed  which  may  be  adjusted  to  grind  to  .00025",  and  the 
feed  is  automatically  stopped  when  the  work  is  ground  to  the  required 


size. 


P2 


The  table  is  moved  by  hand  by  hand- wheel  H  1,  and  by  turning 
a  knob  the  automatic  mechanism,  by  which  the  table  is  fed,  is  set  in 
motion.  The  table  may  be  swiveled  on  a  central  stud  31/2°  each  side 
of  zero.  The  object  of  thus  swiveling  the  table  is  to  provide  for  grind- 
ing slight  tapers.  For  grinding  abrupt  tapers  and  certain  kinds  of 
disk  work  the  head-stock  may  be  swiveled  to  any  required  angle. 

Work  Done  on  Grinders. — As  a  rule  the  universal  grinder  is  not  used 
for  heavy  cutting,  but  to  correct  small  imperfections;  therefore  the 
work  done  on  this  machine  is  generally  made  nearly  right,  as  to  dimen- 
sions, in  the  lathe  or  other  machine.  In  addition  to  such  work  as 
machine-shafts,  etc.,  the  universal  grinder  is  also  used  for  grinding 
lathe-arbors,  reamers,  and  various  angular  and  tapering  shapes. 

Formerly,  grinding  machine-shafts,  etc.,  was  considered  a  very  expen- 
sive process,  and  it  was  dispensed  with  except  in  special  cases.  Recently, 


476 


MACHINE-SHOP  TOOLS  AND  METHODS 


however,  grinding-machmes  and  processes  have  been  studied  and 
developed  to  such  an  extent  that  grinding  is  coming  into  use,  as  a  mat- 
ter of  economy,  on  a  great  deal  of  work  where  the  refinements  of  the 


process  are  not  strictly  necessary.  A  specialist  in  grinding  can  make 
the  finishing  cuts  on  all  kinds  of  cylindrical  work  at  less  cost  than  is 
possible  with  ordinary  lathe  processes.  In  some  classes  of  work  the 
lathe  is  dispensed  with,  and  both  roughing  and  finishing  cuts  are  made 
In  the  grinder.  This  is  especially  true  of  the  plain  grinder. 


GRINDING  MACHINES  AND  METHODS 


477 


In  most  kinds  of  work  it  is  ^necessary  to  keep  water  running  on  the 
wheel  when  grinding,  and  for  this  purpose  a  pump  attached  to  the  rear 
of  the  machine  automatically  supplies  the  water. 

Grinding  Parallel  Shafts. — About  the  simplest  operation  on  the 
grinder  is  that  of  grinding  a  plain  shaft  parallel  in  diameter.  In  per- 
forming this  work  the  shaft  is  placed  between  the  centers  with  a  dog 
on  the  head-stock  end,  the  swivel-table  is  set  to  zero,  and  with  the 
machine  in  motion  the  emery-wheel  is  fed  up  against  the  work  by  hand. 
For  traversing  the  table  the  automatic  longitudinal  feed  is,  of  course, 
used.  If  the  grinding  is  to  approach  very  close  to  the  dog  or  to  the 
foot-stock  spindle  it  will  be  necessary  to  use  care  in  adjusting  the  tap- 


FIG.  657. 

pets  which  regulate  the  traverse  of  the  table.  If,  for  instance,  the 
tappet  next  to  the  head-stock  end  be  moved  too  far  to  the  left,  the 
emery-wheel  may  strike  the  dog,  causing  the  wheel  to  burst.  It  is 
safer  to  first  adjust  the  tappets  for  a  too  short  traverse  and  make  the 
correction  after  noting  how  far  the  table  falls  short  of  the  required 
stroke.  It  is  important  also  in  this  and  other  grinding  operations 
that  the  hood  which  covers  the  emery-wheel  be  used. 

In  most  grinding-machines,  if  not  all,  it  is  difficult  to  adjust  the 
table  at  the  first  setting  to  grind  a  shaft  parallel.     Having  adjusted 


-478 


MACHINE-SHOP  TOOLS  AND  METHODS 


the  table  as  nearly  as  may  be  by   the   graduations  at  the   end,  the 
-cut-and-try  method  must  be  used  for  making  the  final  corrections. 

In  some  classes  of  work,  in  which  it  is  necessary  to  grind  close  to  a 
shoulder,  it  is  permissible  to  turn  a  groove  about  1/4//  wide  next  to 
the  shoulder.  This  obviates  the  necessity  of  having  the  emery-wheel 


touch  the  shoulder.  The  diameter  at  the  bottom  of  the  groove  need 
not  be  more  than  about  .001"  less  than  the  diameter  of  the  shaft.  If  it 
Is  necessary  to  grind  to  a  sharp  corner  under  the  shoulder  without  the 
preliminary  grooving,  it  will  be  advantageous  to  begin  grinding  at  the 
shoulder  and  feed  the  other  way.  By  this  method  the  advancing  corner 


GRINDING  MACHINES  AND  METHODS 


479 


of  the  wheel  will  do  the  most  of  the  work,  and  the  wear  of  the  wheel 
will  leave  the  opposite  corner  sfyarp  for  the  next  cut  under  the  shoulder. 
This  is  the  method  followed  at  •.the  works  of  The  Brown  and  Sharpe 
Manufacturing  Company: 


FIG.  659. 


In  grinding  a  long  shaft  the  parallelism  of  the  shaft  is  affected  by 
the  wear  of  the  emery-wheel.  To  reduce  this  wear  to  a  minimum,  a 
wheel  having  a  comparatively  wide  face  should  be  used  and  the  feed  should 
be  correspondingly  faster.  The  machine  grinds  during  both  the  forward 
and  backward  traverse  of  the  table,  and  this  in  part  compensates  for  the 
wear  in  the  wheel. 


480 


MACHINE-SHOP  TOOLS  AND  METHODS 


Use  of  the  Back-rest. — It  has  been  shown  elsewhere  that  in  turning 
long  slender  work  in  the  lathe  it  is  necessary  to  use  a  steady  rest,  or  back- 
rest, to  support  the  work  against  the  pressure  of  the  cut.  The  back-rest 
shown  in  Fig.  657  is  used  for  a  similar  purpose  in  the  Universal  grinder. 
The  shoes  or  lugs  which  support  the  work  may  be  made  of  some  soft 
metal  or  hard  wood.  Fig.  658  shows  the  Universal  back-rest.  This  rest 
admits  of  more  delicate  adjustment  and  is  better  for  some  kinds  of 
work,  especially  shafts  having  keyways.  Work  in  which  the  diameter 
is  very  small  in  proportion  to  the  length  requires  the  use  of  several  rests. 
One  rest  for  a  length  of  about  every  eight  diameters  should  be  sufficient. 

Grinding  Tapers. — As  has  been  indicated  the  upper  part  of  the  table 
swivels  on  a  central  stud  and  is  graduated  at  the  end.  This  provision 
enables  the  table  to  be  adjusted  for  grinding  slight  tapers.  In  other 


FIG.  660. 

respects  the  grinding  of  these  tapers  does  not  differ  from  grinding  parallel 
work.  It  may  be  observed,  however,  that  this  method,  which  does  not 
disturb  the  fit  of  the  centers,  is  much  superior  to  the  method  of  turning 
tapers  in  the  lathe  by  setting  over  the  tail-stock.  It  is  even  more  reliable 
than  the  compound-rest  method. 

The  table  will  not  swivel  sufficiently  for  abrupt  tapers  like  that 
shown  in  Fig.  659.  For  such  work  the  table  is  set  to  zero  and  the  wheel- 
bed  adjusted  to  the  required  angle  and  fed  by  the  cross-feed  mechanism. 
As  will  be  seen  in  the  illustration  the  wheel  is  swiveled  to  give  it  a  full 
bearing  on  the  work. 

In  some  cases  a  slight  taper  and  an  abrupt  taper  are  required  on 
the  same  piece  of  work.  In  such  a  case  the  slight  taper  is  ground  by 
swiveling  and  feeding  the  table  as  previously  described,  the  abrupt  taper 
being  ground  as  in  Fig.  659,  excepting  that  the  wheel  is  adjusted  in 


GRINDING  MACHINES  AND  METHODS 


481 


proper  relation  for  the  slight  taper  and  its  corner  beveled  off  to  give  it 
a  sufficient  bearing  on  the  abrupt  taper. 

Grinding  the  Ends  of  Bushings  and  Collars. — In  Fig.  660  is  shown 
one  method  of  grinding  bushings  and  collars.     For  this  purpose  the  wheel 


FIG.  661. 


should  be  so  shaped  as  to  leave  a  narrow  bearing  on  the  side  and  the  bush- 
ing should  overhang  a  shoulder  on  the  arbor.  This  is  necessary  in  order 
that  the  wheel  may  have  sufficient  crosswise  movement  without  touching 
the  arbor.  It  will  be  understood  that  the  cross-feed  is  used  on  such  work. 
Disk -grinding. — Work  the  diameter  of  which  is  much  greater  than 
the  length  may  be  very  conveniently  ground  by  swiveling  the  head-stock 
90°  and  using  the  longitudinal  feed  of  the  table.  Fig.  661  shows  this 
method.  By  varying  the  angle  of  the  head-stock  from  90°  the  face  of 
the  work  may  be  made  either  convex  or  concave.  In  connection  with 
the  swiveling  head-stock  and  chuck  it  should  be  easy  without  any  illustra- 


482 


MACHINE-SHOP  TOOLS  AND  METHODS 


tion  to  conceive  of  a  method  of  grinding  two  surfaces  at  an  angle  to 
each  other.  Thus  the  face  of  the  work  might  be  ground  by  feeding  the 
table  lengthwise  and  its  corner  ground  to  an  angle  with  the  face.  In 
grinding  the  corner  the  cross -feed  should  be  used.  As  indicated  in  a  some- 


what similar  case,  one  corner  of  the  wheel  should  be  beveled  off  to  increase 
its  bearing  on  the  angular  surface. 

Special  Draw-in  Chuck. — The  chuck  shown  in  Fig.  662  is  very  con- 
venient for  thin  disk  work  which  is  required  to  be  held  quite  true  with 
its  bore.  Such  work  is  placed  upon  the  split  bushing  at  C,  which  bush 


GRINDING  MACHINES  AND  METHODS 


483 


ing  is  expanded  by  the  screw  B,  and  the  work  is  drawn  up  firmly  against 
the  face-plate  by  the  knob  A.  Different  sizes  of  bushings  may  be  used  for 
different  bores.  The  method  of  grinding  the  work  is  the  same  as  in  Fig.  661. 


FIG.  663 


Internal  Grinding. — Fig.  663  shows  the  internal  grinding  fixture  and 
Figs.  664  and  665  show  two  classes  of  internal  grinding.     As  will  be 


FIG.  664. 


seen  the  fixture  is  bolted  to  the  wheel  platen  and  driven  by  a  light  belt 
from  the  pulley  L.     The  spindle  which  carries  the  pulley  L  is  driven 


484 


MACHINE-SHOP  TOOLS  AND  METHODS 


from  the  overhead  counter-shaft  by  a  belt  running  on  the  pulley  m.  In 
parallel  work  the  swivel-table  is  placed  at  zero  and  is  fed  in  the  same 
manner  as  for  external  parallel  work.  A  method  of  grinding  slight 
and  abrupt  tapers  is  clearly  indicated  in  Fig.  665.  The  table  is  swiveled 
and  its  longitudinal  feed  operated  for  the  slight  taper.  In  grinding  the 
abrupt  taper  the  cross-feed  is  used.  In  adjusting  the  wheel-slide  for 
this  taper  the  angle  of  the  table  must  be  taken  into  account. 

Surf  ace -grinding  Machines. — Surface-grinding  machines  are  used  for 
grinding  plane  surfaces.     Like  the  grinders  for  cylindrical  work,  these 


FIG.  665. 

machines  are  designed  for  both  roughing  and  finishing  cuts,  and  to  grind 
hardened  steel  which  cannot  be  machined  with  ordinary  tools.  Fig.  666 
shows  a  surface-grinding  machine  constructed  very  much  like  a  metal 
planer.  The  wheel  is  driven  from  the  drum  seen  behind  the  housing, 
which  drum  in  turn  is  driven  from  an  overhead  counter-shaft.  This 
counter-shaft  is  seen  near  the  machine.  The  travel  of  the  table  is  auto- 
matic and  its  stroke  is  regulated  by  adjustable  dogs.  The  cross-rail  is 
adjustable  on  the  housing  castings,  the  front  faces  of  which  are  made 


GRINDING  MACHINES  AND  METHODS 


485 


circular  to  avoid  disturbing  the  tension  of  the  belt.     The   cross-head 
carrying  the  emery  wheel  is  fed  horizontally  on  the  cross-rail  at  the  end 
of  the  stroke  in  very  much  the  same  manner  as  a  planer-tool  is  fed. 
Great  care  is  required  in  clamping  work  to  the  grinder-table  to 


FIG.  666. 


avoid  springing  it.  The  refinements  possible  in  the  grinding  process 
are  easily  neutralized  by  errors  in  clamping.  The  Walker  magnetic 
chucks,  which  are  used  to  some  extent  in  lathe-work,  planer-work,  etc., 
are  of  special  advantage  in  connection  with  the  surface  grinder. 


486 


MACHINE-SHOP  TOOLS  AND  METHODS 


Combined  Drill  and  Surface  Grinder. — Fig.  667  shows  a  combined 
surface  and  drill  grinder.  It  has  an  advantage  over  some  combina- 
tion tools  in  that  both  operations  may  be  performed  simultaneously. 
"A  peculiarity  of  the  drill  holder  is  that  it  does  not  require  adjustment 
for  different  diameters  of  drills,  while  the  adjustment  for  length  is  made 
in  the  usual  manner."  The  table  for  surface  grinding  has  a  vertical 


FIG.  667. 

adjustment,  and  in  connection  with  this  adjustment  a  graduated  dial 
reading  to  thousandths  of  an  inch  is  provided.  The  work  is  not  clamped 
to  the  table,  but  is  fed  along  on  the  table  by  hand. 

Floor  Grinders  with  Surface  Attachment.— The  grinding-machine 
shown  in  Fig.  668  has  an  emery-wheel  at  the  right  end  of  the  spindle 
which  may  be  used  for  miscellaneous  grinding.  Mounted  above  the 
wheel  at  the  left  is  a  surface-grinding  table.  This  table  is  adjustable 


GRINDING  MACHINES  AND  METHODS 


487 


vertically  to  compensate  for  the  wear  of  the  wheel  and  also  for  adjust- 
ing the  depth  of  the  cut.  The  work  is  moved  over  the  revolving  wheel 
by  hand  as  in  Fig.  667.  The  grooves  seen  in  the  table  are  designed 
to  catch  the  particles  of  emery  ancT%rit  from  the  castings  being  ground. 
This  machine  while  very  convenient  for  general  grinding  is  not  adapted 
to  the  high  grade  of  work  for  which  the  machine  in  Fig.  666  is  designed. 
Emery-wheel  Dressers. — In  connection  with  Fig.  647  we  allude  to 
a  truing-roll  used  for  truing  the  wheel  of  that  machine.  The  roll  is 


FIG.  668. 

simply  a  cylinder  having  small  journals  at  each  end  and  having  deep 
grooves  in  the  cylinder,  giving  the  latter  the  -appearance  of  a  series 
of  thin  disks  separated  by  small  washers.  The  roll  is  caused  to  revolve 
by  being  brought  into  contact  with  the  revolving  emery-wheel  by  screw 
pressure.  Increasing  this  pressure  causes  the  roll  to  crush  and  break 
down  the  particles  of  emery.  As  the  roll  touches  the  high  parts  of 
the  emery-wheel  first  and  hardest  the  effect  is  to  "true  up"  the  wheel, 
or  make  its  periphery  concentric  with  the  axis  of  rotation. 


488  MACHINE-SHOP  TOOLS  AND  METHODS 

Shown  near  the  right-hand  wheel  in  Fig.  668  is  another  form  of 
emery-wheel  dresser.  In  using  this  device  the  pressure  is  applied  by 
the  lever,  the  effect  being  to  break  down  the  high  spots  in  the  emery- 
wheel  the  same  as  in  the  case  of  the  truing-roll. 


FIG.  669. 


For  dressing  the  higher  grades  of  emery-wheels  such  as  are  used 
on  the  Universal  grinders,   small  center  grinder,   etc.,   a  cheap  black 


FIG.  670. 

diamond  held  in  the  end  of  a  metal  holder  is  used.  This  holder  has  a 
handle  on  the  outer  end  and  is  applied  to  the  revolving  emery-wheel 
in  about  the  same  way  that  a  hand-tool  is  used.  Holders  are  made 


GRINDING  MACHINES  AND   METHODS 


489 


also  of  such  shape  as  to  admit  of  being  held  in  a  kind  of  tool-post  pro- 
vided for  this  purpose. 

Grinding  Attachment  for  the  Lathe. — A  first-class  machine  for 
cylindrical  grinding  is  a  -costly  t(M.  Many  small  machine-shops  which 
could  not  afford  a  regular  machine  would  find  the  attachment  illustrated 
in  Figs.  669  and  670  very  useful.  This  attachment  is  held  upon  the 
tool-rest  in  place  of  the  tool-post  and  is  driven  from  an  overhead  drum 


FIG.  671. 

counter-shaft  which  is  furnished  with  the  attachment.  In  the  first  illus- 
tration it  is  shown  grinding  an  arbor.  For  internal  grinding  the  spindle 
is  removed  and  another  spindle  is  used  instead,  as  shown  in  Fig.  670. 

Portable  Emery-grinder. — Fig.  671  shows  a  portable  emery-grinder 
and  the  method  of  applying  it  in  polishing  and  grinding  framework,  etc. 
By  using  suitable  wheels,  it  may  be  employed  for  grinding  heavy  cast- 
ings, for  cleaning,  polishing,  buffing,  etc.  It  is  driven  by  a  counter- 
shaft, rope,  and  flexible  shaft  as  shown. 

Speed  of  Emery-wheels. — In  general  an  emery-wheel  should  be  run 
at  the  speed  recommended  by  the  manufacturers.  For  most  purposes 
this  speed  will  not  be  much  greater  than  5000  feet  per  minute.  Ex- 
perts in  special  lines  of  work  sometimes  run  as  fast  as  about  6500  feet 


490  MACHINE-SHOP  TOOLS  AND  METHODS 

per  minute,  but  on  account  of  the  great  danger  of  the  wheel  bursting, 
excessively  high  speeds  are  not  to  be  encouraged. 

Work  Speed  and  Rate  of  Wheel  Traverse.— It  is  difficult  to  give 
rules  for  the  work  speed  and  the  traversing  feed  of  emery-wheels  as 
used  in  the  Universal  and  plain  grinders.  In  the  early  days  of  cylin- 
drical grinding,  the  work  was  rotated  at  a  high  speed, — in  some  cases 
as  high  as  400  to  500  feet  per  minute.  The  traversing  feed  was 
about  Vioo  to  3/ioo  inch  per  revolution  of  work.  With  improvements 
in  the  emery-wheels  and  further  experiments  it  was  learned  that  better 
results  could  be  obtained  with  slower  work  speeds  and  faster  traversing 
feeds.  At  present  very  few  mechanics  run  the  work  faster  than  100 
feet  per  minute.  A  feed  of  i/4  to  3/4  inch  per  revolution  of  work  in 
machines  of  ordinary  size  is  perhaps  in  accordance  with  conservative 
practice.  Mr.  Landis,  an  expert  in  the  use  of  grinding-machines,  recom- 
mends a  range  of  from  25  to  80  feet  per  minute,  with  a  feed  of  one  half 
to  three  fourths  the  width  of  the  wheel-face.  Mr.  C.  H.  Norton,  another 
authority,  says:  "At  the  present  time  the  best  and  quickest  work  is  done 
at  a  work  speed  of  from  6  to  40  feet  per  minute."  *  Mr.  Norton  thinks 
that  the  feed  should  equal  the,  width  of  the  wheel-face,  and  states  that 
he  has  used  wheels  of  1"  to  4"  face. 

In  a  pamphlet  entitled  "A.  Few  Points  on  Grinding,"  Mr.  Norton 
tells  of  some  astonishing  results  which  were  accomplished  by  a  nice 
adjustment  of  the  relations  between  work  speed,  wheel  speed,  and 
feed  and  wheel  grade.  He  claims  that  one  cubic  inch  of  steel  may  be  re- 
moved per  minute  in  cylindrical  grinding  when  all  the  conditions  are 
favorable.  Those  mechanics  who  have  been  accustomed  to  the  use  of 
wheels  beveled  at  the  edge  to  give  a  bearing  on  the  work  of  1/8//  to  3/s", 
with  corresponding  feeds,  should  study  recent  developments  in  grinding 
machines  and  processes.  It  is  evident  that  the  possibilities  of  these 
machines  in  both  cylindrical  and  surface  grinding  have  been  greatly 
underestimated. 

Glazing.— When  the  "bond"  is  too  hard  it  does  not  wear  away  fast 
enough  to  allow  the  emery  to  cut,  and  the  wheel  becomes  glazed.  A 
glazed  wheel  will  not  cut  freely,  but  will  heat  the  work  and  cause  it 
to  spring  between  the  centers.  Glazing  may  usually  be  prevented  by 
either  reducing  the  speed  or  using  a  softer  wheel. 

Coarse  and  Fine  Wheels. — A  coarse  wheel  will  generally  give  a 
better  finish  on  tempered  steel  and  other  hard  materials,  while  a  fine 
wheel  will  give  best  results  on  brass,  copper,  etc. 

*  "  American  Machinist,"  Jan.  7,  1904,  page  17. 


GRINDING  MACHINES  AND  METHODS  491 

Causes  of  Chattering. — The  causes  of  chattering  in  cylindrical  grind- 
ing are  not  altogether  different  from  those  which  produce  a  similar  result 
in  lathe  work.  Small  wheel-spinciles,  loose  wheel-spindles,  unbalanced 
wheels,  small  work-centers,  small  machine-centers,  loose  fits  in  the 
sliding  parts,  long  work  not  properly  supported  with  back-rests,  high 
work  speeds,  and  wheels  too  hard  for  the  work,  are  some  of  the  causes  of 
chattering.  A  knowledge  of  the  cause  will  generally  suggest  the  remedy. 
Reducing  the  width  of  wheel-face  and  feed  will  in  some  cases  prevent 
chattering,  but  as  this  lessens  the  quantity  of  work  the  other  remedies 
should  first  be  applied  as  far  as  practicable. 

Mounting  the  Wheel. — It  is  absolutely  necessary  to  safety  in  operation 
that  a  wheel  fit  freely  on  the  spindle,  and  that  some  kind  of  elastic  washers 
be  used  between  the  flanges  and  the  wheel.  For  the  latter  purpose 
rubber,  pasteboard,  or  blotting-paper  may  be  used. 

Uses  of  Water  in  Cylindrical  Grinding.  Causes  of  Eccentricity. — It 
is  very  important  in  heavy  grinding  of  work  between  centers  to  keep  the 
work  cool.  For  this  purpose,  the  grinding-machine  is  furnished  with  a 
pump  and  a  very  liberal  and  even  supply  of  water  should  be  used.  It  is 
said  that  a  degree  of  heat  which  is  imperceptible  to  the  touch  will  curve  the 
work.  A  very  slight  degree  of  curvature  may  be  detected,  being  shown 
by  sparks  on  the  convex  side  of  the  work.  In  such  cases  as  require  a 
small  amount  of  very  light  grinding  on  each  piece,  and  especially  in  short 
chuck  work,  water  may  be  dispensed  with. 

The  smallest  speck  of  grit  between  the  machine-center  and  the 
work-center  will  cause  eccentricity.  Now,  this  speck  of  grit  is  likely  to 
wear  away  during  the  process  of  grinding,  and  this  would  cause  a  vary- 
ing degree  of  eccentricity.  Eccentricity  may  also  be  caused  by  wear 
of  the  centers  due  to  lack  of  oil,  or  by  the  centers  being  made  too  small. 
The  work-centers  should  be  amply  large,  they  should  fit  the  machine- 
centers  so  as  to  insure  a  full  bearing,  and  they  should  be  kept  scrupulously 
clean  and  well  oiled. 


CHAPTER  XXIX 
POLISHING-  AND  BUFFING-WHEELS 

Polishing-  and  Buffing-lathe. — In  connection  with  this  machine, 
which  is  shown  in  Fig.  672,  a  variety  of  polishing-wheels  and  materials 
are  employed.  The  polishing-wheels  are  held  between  the  collars  on 
the  spindle  in  about  the  same  manner  as  emery-wheels  are  held,  and  the 
article  to  be  polished  is  applied  to  the  revolving  wheel  by  hand.  The 
over-hang  of  the  spindle  and  its  bearings  affords  convenient  access  to 
both  sides  of  the  wheel  as  well  as  to  its  periphery.  Among  the  different 
polishing-wheels  used  in  the  buffing-lathe  are  wooden  wheels,  walrus- 
wheels,  brush-wheels,  rag-wheels,  felt-wheels,  paper-wheels,  and  canvas- 
wheels. 

Wooden  Wheels. — Leather-covered  wooden  wheels  are  employed  for 
various  classes  of  polishing.  These  wheels  are  made  of  wood,  whitewood 
being  suitable.  The  wood  is  built  up  on  a  metal  bushing  in  broken-joint 
sections  after  the  manner  of  pattern-making.  Oak-tanned  sole-leather 
about  1/4"  thick  makes  a  good  covering.  After  slightly  moistening  the 
leather  in  hot  water  it  should  be  stretched  around  the  wheel,  flesh  side 
in,  and  glued,  the  glue  being  quite  hot.  To  assist  in  holding  the  leather, 
metal  tacks  may  be  used  temporarily,  but  these  should  be  replaced  by 
wooden  pegs  driven  below  the  surface  of  the  leather. 

The  leather  is  coated  with  emery,  which  may  vary  from  No.  60  for  the 
preparatory  work  to  flour  emery  for  finishing.  In  applying  the  emery 
the  leather  is  first  coated  with  hot  glue.  The  wheel  is  next  quickly 
rotated  over  a  planed  board,  upon  which  the  emery  has  been  evenly 
spread.  These  wheels  give  a  fairly  good  surface  on  cast  iron,  wrought 
iron,  and  steel,  flour  emery  being  used  for  the  finishing  process. 

For  obtaining  a  higher  finish  or  polish  a  " grease  wheel"  may  be 
used.  A  wheel  "set  up"  with  flour  emery  and  glazed  or  worn  smooth 
will  answer.  The  oil  or  grease  may  be  applied  to  the  wheel  by  any 
convenient  means  while  the  wheel  is  in  motion.  If  oil  be  used,  it  may 
be  applied  with  a  thick  cloth.  If  cake  tallow  be  preferred,  care  should 
be  taken  to  give  the  wheel  a  very  thin  coating.  Fine  emery-cake 

492 


POLISHING-  AND   BUFFING-WHEELS  49$ 

applied  to  the  wheel  after  it  has  been  greased  will  make  a  good  pol- 
ishing material. 

J]rass   also  may  be  polished  oa  emery-coated  wooden  wheels.      It 
may  be  roughed  down  with  emery  and  finished  with  red  rouge  or  other 


FIG.  672. 

suitable  polishing  material,  cake-tallow  being  used  for  the  preparatory 
greasing.  Before  greasing  it  the  surface  of  the  wheel  should  be  glazed 
as  above  described.  i 

Walrus -wheels. — Walrus  (or  sea-horse)  hide  cut  into  disks  and 
glued  together  makes  a  first-class  polishing-wheel.  A  variety  of  polish- 
ing materials  is  used  with  these  wheels.  Emery  may  be  applied  in  con- 
nection with  glue  in  the  same  manner  as  in  the  case  of  wooden  wheels. 


494  MACHINE-SHOP  TOOLS  AND  METHODS 

Walrus-wheels  may  be  used  as  grease  wheels  also.  Some  prefer  to 
keep  these  wheels  for  the  final  finishing,  using  crocus  or  rouge  for  this 
purpose.  When  thus  used  the  emery  and  glue  coating  may  be  dis- 
pensed with.  Walrus-wheels  are  principally  used  for  polishing  tools 
and  cutlery,  but  they  are  also  used  to  some  extent  in  polishing  brass. 
Powdered  pumice-stone  mixed  with  oil  and  applied  to  the  wheel  with 
a  brush  makes  a  good  preparatory  surface  on  brass.  Crocus,  rouge, 
or  nickel  rouge  may  be  used  to  give  the  final  polish.  Nickel  rouge  is 
also  used  for  polishing  nickel.  Vienna  lime  dipped  in  oil  and  applied 
to  the  revolving  walrus-wheel  will  give  a  fine  finish  on  iron  and  steel. 
Crocus  and  nickel  rouge  come  in  cakes  and  may  be  applied  to  the 
revolving  wheel  by  hand  without  oil. 

Brush-wheel. — This  is  a  kind  of  circular  brush,  the  hair  being  held 
in  the  brush  in  about  the  same  manner  as  in  a  common  brush.  Vienna 
lime  is  often  used  on  these  wheels.  In  polishing  steel  or  iron  the  lime 
is  preceded  by  oil  and  emery,  these  being  applied  in  any  convenient 
manner.  Crocus  or  rouge  mixed  with  water  or  oil  may  be  used  on 
brush-wheels  for  both  brass  and  steel.  To  get  the  best  results  these 
materials  should  be  preceded  by  powdered  pumice-stone  mixed  with  oil. 

Rag-wheels. — Rag-wheels,  or  buffs,  admit  of  wide  application  as 
polishing-wheels,  but  they  are  not  adapted  to  work  requiring  the  corners 
to  be  kept  sharp.  They  may  be  used  on  about  all  the  common  metals, 
different  polishing  materials  being  used  to  suit  each  case.  For  polish- 
ing steel  and  iron  a  composition  of  Vienna  lime,  crocus,  and  beeswax 
is  sometimes  used.  This  material  comes  in  cakes  and  it  is  dipped  in 
oil  and  applied  sparingly  to  the  revolving  wheel.  Crocus  mixed  with 
tallow  and  oil  is  used  on  rag-wheels  for  polishing  fine  steel  goods  and 
for  brass  and  plated  work.  It  is  especially  adapted  to  nickel  plate 
Crocus  alone  is  often  used  on  these  wheels,  being  rubbed  on  while  the 
wheel  is  in  motion.  Rouge  is  used  on  rag-wheels  for  steel,  iron,  nickel 
plate,  brass,  bronze,  and  copper.  It  is  sometimes  mixed  with  alcohol 
and  water  (equal  parts  of  each)  into  a  thin  paste.  In  this  form  it  may 
be  applied  to  both  the  wheel  and  the  work  with  the  finger. 

Glue  and  emery  coatings  are  not  used  on  rag-wheels.  As  above  indi- 
cated, various  compounds  are  applied  to  the  wheels  during  the  progress 
of  the  work. 

In  using  any  of  the  polishing  agents,  such  as  rouge,  crocus,  etc., 
it  is  best  to  apply  the  material  sparingly  and  often,  rather  than  in  thick 
coatings.  The  work  is  delayed  rather  than  hastened  by  a  too  free 
use  of  the  polishing-cake. 


POLISHING-  AND  BUFFINGHE  495 


When  it  is  necessary  to  preserve  the  exact  shape  of  the  work,  espe- 
cially when  corners  are  to  be  kep^  sharp,  the  surface  of  the  wheel  should 
be  approximately  unyielding.  Leather-covered  wooden  wheels  are  com- 
monly used  for  such  requirements,  but  to  get  the  best  results  the  wheel 
should  be  covered  with  sheet  lead  instead  of  leather. 

The  Emery-stick.  —  This  is  simply  a  stick  of  wood  coated  with  alter- 
nate layers  of  hot  glue  and  emery.  It  is  used  to  remove  the  old  glue 
and  emery  from  a  wheel  before  recharging  with  new  emery.  The  stick 
is  held  against  the  revolving  wheel,  care  being  taken  to  avoid  applying 
sufficient  pressure  to  injuriously  heat  the  leather. 

Rag-wheels  may  be  cleaned  by  applying  the  point  of  an  old  file 
to  the  revolving  wheel. 

Speed  of  Polishing-wheels.  —  Wooden  wheels  are  run  at  a  speed  of 
6000  to  7000  feet  per  minute.  As  there  is  danger  in  such  high  velocities, 
it  is  important  that  these  wheels  be  purchased  of  experienced  and  reli- 
able manufacturers.  No  novice  should  attempt  to  make  one. 

Walrus-wheels  may  be  run  at  a  velocity  of  7000  to  8000  feet  per 
minute.  They  are  not  so  likely  to  fly  apart  as  are  wooden  wheels. 

Brush-wheels  are  made  in  sizes  as  small  as  2"  diameter.  It  is  not 
convenient  to  run  such  small  sizes  at  a  high  surface  speecl,  but  the  larger 
sizes  are  sometimes  run  as  fast  as  5000  feet  per  minute. 

Buffs  or  rag-wheels  are  run  at  about  6500  feet  for  coloring  and  as  high 
as  13,000  to  14,000  feet  per  minute  for  "  cutting-down"  or  preparatory 
work. 

In  finishing  castings  or  other  materials  which  have  not  been 
machined,  the  work  should  have  a  thin,  smooth  scale.  If  the  surface 
be  deeply  pitted,  too  much  time  will  be  required  to  finish  it.  Canvas- 
wheels,  set  up  in  No.  80  emery,  are  well  adapted  to  the  first,  or  cutting- 
down,  process  in  such  work. 


CHAPTER  XXX 
THE  INTERCHANGEABLE  SYSTEM  OF    MANUFACTURE 

Jigs. — By  the  interchangeable  system  is  meant,  such  shop  methods 
as  enable  the  manufacturer  to  furnish  duplicate  parts  to  replace  broken 
or  worn-out  parts  of  his  machines.  Of  fundamental  importance  in  such 
a  system  are  accurate  measuring-instruments.  These  have  already 
been  described.  Next  in  importance  are  jigs  and  special  fixtures  for 
the  accurate  and  rapid  machining  of  the  duplicate  pieces.  If  an  engine- 
cylinder  head  is  to  be  drilled  to  receive  the  studs  which  secure  it  to  the 
cylinder,  one  of  two  ways  could  be  used.  The  head  could  be  carefully 
laid  out  by  rule  and  compass  and  drilled  to  the  marks,  or  a  device  could 
be  made  to  fit  over  the  cylinder-head  having  holes  in  exactly  the  right 
positions  to  guide  the  drill.  Such  a  device  is  called  a  jig,  and  it  pays 
to  make  this  tool  when  a  large  number  of  duplicate  pieces  are  to  be 
manufactured.  Should  one  of  these  cylinder-heads  need  to  be  replaced 
after  shipping  the  engine,  if  drilled  by  a  jig  a  new  one  could  be  sent 
with  the  assurance  that  it  would  require  no  refitting. 

Inasmuch  as  the  jig  is  used  for  a  large  number  of  duplicate  parts 
it  is  essential  not  only  that  it  be  made  with  great  accuracy,  but 
that  provision  be  made  for  maintaining  this  accuracy.  With  this  end 
in  view  the  guiding-holes  in  the  jig  are  not  allowed  to  come  in  contact 
with  the  drill  or  reamer  (which  would  wear  them  out  of  shape) ,  but  are 
made  larger  and  bushed,  as  at  B,  Fig.  673.  If  the  holes  through  the 
cylinder-head  are  5/s",  the  holes  in  the  jig  should  be  about  ll/s",  and 
bushings  with  s/8"  holes  should  be  inserted  to  guide  the  drill.  The 
bushings  are  sometimes  made  of  tool  steel  and  hardened,  which  makes 
them  very  durable;  but  inasmuch  as  the  hardened  bushings  may  injure 
the  drill,  or  reamer,  some  mechanics  make  them  of  cast  iron  and  renew 
them  when  worn.  Renewing  the  bushings  is  an  inexpensive  process  com- 
pared with  renewing  the  whole  jig,  and  it  does  not  in  the  least  affect  the 
original  accuracy  of  the  jig. 

The  same  jig  is  in  some  cases  used  for  both  the  cylinder-head 
and  the  flanges  on  the  ends  of  the  cylinder;  but  as  the  holes  in  the 

496 


THE  INTERCHANGEABLE  SYSTEM  OF  MANUFACTURE        497 

cylinder-flanges  are  made  smaller  to  allow  for  thread  on  the  studs,  the 
jig  requires  an  extra  set  of  bushings  for  the  smaller  holes.  Otherwise  a 
special  drill  would  be  necessary. 

It  is  frequently  necessary  to  make  jigs  for  work  which  is  only  partly 
machined.     If  we  require  a  jig  for  the  steam-chest  cover  of  a  steam- 


FIG.  673. 


FIG.  674. 


engine,  and  only  three  edges  of  the  cover  are  planed,  the  jig  could  be 
made  with  planed  lugs  fitting  the  planed  edges  of  the  steam-chest  cover, 
the  holes  being  laid  out  with  reference  to  these  planed  edges.  The 
jig  should  be  secured  to  the  steam-chest  cover  by  set-screws  in  lugs, 
which  set-screws  should  press  against  the  rough  edge  of  the  cover,  as 
shown  in  Fig.  674. 

An  excellent  example  of  jig-making  and  jig  work  is  shown  in  Figs. 
675,  676,  677,  and  678.*  Fig.  675  is  a  working  drawing  of  a  side-frame 
of  a  small  machine  to  be  drilled  and  reamed.  The  dimensions  are  given 
to  the  third  decimal  place,  thus  indicating  the  degree  of  accuracy  required. 
There  are  two  of  these  frames  for  each  machine,  and  as  they  are  very 
nearly  alike,  the  jig  for  the  drilling  is  made  reversible,  so  that  after  drilling 
one  frame,  the  other  may  be  secured  to  the  opposite  side  of  the  jig  and 
drilled  in  a  similar  manner. 

Fig.  676  shows  the  jig.  The  main  casting  D  which  holds  the  bushings 
has  four  feet,  lettered  (7,  by  which  the  jig  is  supported  on  the  drilling- 
machine.  These  feet  are  hardened  tool  steel.  The  frame  is  held  between 
the  "  supporting-plate "  E  and  bushing-plate  D  by  the  clamps  G.  The 


*  These  cuts  were  first  used  to  illustrate  an  article  by  W.  H.  Pike,  Jr.,  in  "Ameri- 
can Machinist,"  vol.  24,  page  1296. 


498 


MACHINE-SHOP  TOOLS  AND  METHODS 


THE  INTERCHANGEABLE  SYSTEM  OF  MANUFACTURE        499 


bushing-holes  in  plate  D  are  all  of  the  same  diameter  as  are  also  the  holes 
in  the  bushings.    This  uniformity  simplifies  the  making  of  the  bushings 

4 


rUJ — '.Liili  i"     if!    Jiff    --V     i-L.!    I  \''  V'iS' — "    ^•"•^>         '  '     ':  !  |!'    $ 


FIG.  676. 

and  facilitates  accurate  location  of  the  holes  for  the  bushings.  The  latter 
were  bored  and  reamed  on  a  milling-machine  and  "the  position  verified 
by  height-gage  and  vernier."  To  equalize  the  strains  in  the  castings  due 
to  forcing  in  the  bushings,  some  were  forced  from  one  side  and  some  from 
the  other. 

An  important  feature  in  connection  with  this  jig  is  the  method  of 
guiding  the  drills  and  reamers.     These  do  not  touch  the  bushings,  being 


FIG.  677. 

held  in  the  special  sockets,  as  shown  in  Fig.  677.  The  lower  ends  of 
these  sockets  are  hardened  and  ground  to  fit  the  bushings.  This 
arrangement  prevents  in  a  great  measure  the  wear  of  bushings  and  tools. 


500 


MACHINE-SHOP  TOOLS  AND  METHODS 


The  various  sizes  of  drills  and  reamers  used  in  the  sockets  project  just 
far  enough  to  pass  through  the  work. 


FIG.  678. 


1 


FIG.  679. 


li  men-can  Xachinitt 

FIG.  680. 


Fig.  678  is  a  bottom  view  of  the  jig  with  the  side-frame  in  place.  The 
two  planed  feet  of  the  frame  abut  against  the  guide-plates,  which  are 


THE  INTERCHANGEABLE   SYSTEM  OF  MANUFACTURE        501 

shown  at  B  in  Fig.  676.     The  third  locating-point  is  a  hole  drilled  before 
to  the  milling  of  the  feet,  and  from  whict  the  milling  was  gaged. 

Figs.  679  and  680,  which  arej;aken  from  an  article  by  " Cherry  Red" 
in  "  American  Machinist/'  vol.  2?,  page  357,  show  a  jig  for  drilling  the 


FIG.  681. 

clamp-levers  used  on  the  tail-stock  of  a  lathe.  The  bushing  is  threaded, 
and  when  screwed  down  upon  the  ball  end  of  the  lever,  automatically 
centers  it.  The  angle  of  the  handle  to  the  drilled  hole  is  regulated 
by  the  adjustable  V  block  shown. 

The  jig  shown  in  Fig.  681,  the  cut  of  which  is  taken  from  "  American 
Machinist,"  dated  September  29,  1888,  needs  but  little  explanation.   The 


central  hole  of  the  lathe-handle  may  first  be  drilled  in  connection  with 
the  bushing  a  and  adjustable  seat  b.     The  handle  is  then  placed  in  the 


502 


MACHINE-SHOP  TOOLS  AND  METHODS 


jig  as  shown,  for  drilling  the  end  hole,  the  central  hole  fitting  the  stem  c. 
In  order  to  drill  holes  different  distances  between  centers  the  stem  c  is 
adjustable  in  a  slot. 

Jigs  are  used  not  only  in  the  drilling-machine  but  also  in  connection 
with  the  planer,  milling-machine,  etc.     When  used  on  these  machines 


c 

C 

C 

C 

C 

C 

N 

B 

B 

B 

B 

B 

B 

m 

Castings 

Castings 

in 

B 

B 

B 

B 

B 

B 

N 

I 

>                 F 

'         l< 

>                  F 

I 

5 

y 

American  Machinist 


FIG.  683. 


the  jig  is  sometimes  called  a  "  fixture."  Fig.  682  shows  three  views 
of  a  device  which  is  to  be  accurately  machined  so  that  duplicates  may 
be  interchangeable.  Some  of  the  smaller  parts,  including  the  plate  V 


„     The  Wcrfc 


FIG.  684. 


and  brass  key  /,  are  bolted  to  the  main  casting  and  will  not  be  included 
in  this  description.     Neither  will  the  drilling  and  reaming  operations 


THE   INTERCHANGEABLE  SYSTEM  OF  MANUFACTURE        503 

be  considered,  such  operations  being  described  in  connection  with  other 

jigs- 

The  first  operation  of  squaring, up  the  sides,  etc.,  is  done  in  a  jig  or 

fixture,  ten  castings  being  milled  at  one  time. 

For  the  second  operation,  viz.,  that  of  milling  the  dovetail  B  and 
the  gibway  C,  the  jig  shown  in  Fig.  683  is  used.  This  jig,  which  is 
shown  broken  in  the  illustration,  holds  eight  castings.  The  jig  is 
accurately  machined  at  all  essential  points,  and  the  castings  are 
held  against  the  locating-lugs  P  by  the  set-screws  in  lugs  L.  In  the 
other  direction,  the  screws  in  lug  N  force  the  castings  up  against  a 
machined  face  not  shown.  The  jig  is  accurately  located  on  the  miller- 
table  by  the  fitting  of  the  tongue  Q  in  the  T  slot  of  the  table.  Being 
thus  located,  the  dovetailed  surfaces  B  are  milled  one  at  a  time  with 
an  angular  cutter.  Then  the  surface  C  is  milled  with  a  plain  cutter, 
a  vertical  milling  attachment  being  used  in  these  operations. 

The  next  operation  is  that  of  milling  the  curved  surfaces  DD.  For 
this  work  the  jig  shown  in  Fig.  684  is  employed,  a  formed  milling-cutter 


FIG.  685. 


being  used  on  each  casting  separately.  The  method  of  holding  the 
work  in  this  jig  is  clearly  shown  in  the  illustration. 

The  drilling  was  done  next,  but  of  this  we  shall  not  speak. 

The  deep  slot  or  keyway  was  milled  as  shown  in  Fig.  685,*  a  number 
of  castings  being  held  in  the  fixture  and  milled  in  one  operation. 

This  may  seem  like  a  very  expensive  outfit  for  such  work,  but  when 
a  large  number  of  pieces  are  to  be  made,  the  first  cost  of  the  fixtures  is 
fully  justified.  Not  only  may  the  work  be  done  much  quicker  than 
by  the  old  method,  but  less  skilful  labor  may  be  employed.  Jig-making 
itself,  however,  requires  a  high  degree  of  skill,  and  the  question  as  to 
whether  it  pays  to  make  a  jig  or  not  depends  upon  the  number  of  pieces  that 
are  to  be  made. 

*  Figs.  682  to  685  are  from  cuts  accompanying  an  article  by  Joseph  V.  Wood- 
worth  in  "American  Machinist,"  vol.  26,  pages  1434  to  1435. 


504  MACHINE-SHOP  TOOLS  AND  METHODS 

Some  jig-makers  leave  a  space  between  the  work  and  the  lower 
end  of  the  bushing  about  equal  to  the  diameter  of  the  drill  or  reamer. 
The  object  in  this  is  to  allow  the  chips  to  lift  out  of  the  hole  without 
working  up  in  between  the  tool  and  bushing  and  wearing  the  latter. 

Various  special  fixtures  are  shown  in  connection  with  milling- 
machine  work  in  Chapter  XXVI. 

Machine  Nomenclature. — Another  very  important  requirement  in 
connection  with  the  interchangeability  of  machine  details  is  a  system  of 
machine  nomenclature.  By  this  we  mean  a  plan  of  symbolizing  machines 
and  parts  of  machines.  Different  manufacturers  have  different  systems, 
but  a  very  simple  plan  is  to  give  each  different  design  of  machine  a  letter, 
or  a  combination  of  letters,  and  each  part  of  the  machine  a  number. 
Thus,  the  first  machine  could  be  A,  and  the  first  piece  of  this  machine 
would  be  No.  1;  and  if  there  were  a  thousand  pieces  in  the  machine  the 
last  would  be  No.  1000.  The  machine  as  a  whole  would  be  known  by 
its  letter,  and  the  details  would  be  designated  by  the  machine  letter 
and  detail  numbers.  The  first  piece  on  machine  A  would  be  marked 
A  1,  the  second  piece  A  2,  etc.  The  next  different  machine  built  would 
be  designated  as  B,  and  its  parts  B  1,  B  2,  B  3,  etc. 

If  any  detail  of  a  machine  be  slightly  altered,  we  may  indicate  this  by 
giving  it  a  sub-letter;  for  instance,  A  1  when  first  changed  would  become 
A  la,  the  second  change  would  be  A  16,  and  so  on.  If  sufficient  changes 
were  made  to  use  all  the  letters  of  the  alphabet,  the  piece  would  be  so 
different  from  the  original  as  to  justify  a  new  number.  This  would  be  the 
next  number  above  the  highest  number  in  the  machine. 

As  indicated  above,  when  all  the  letters  of  the  alphabet  are  taken,  the 
machine  may  be  symbolized  by  combining  the  letters.  Thus,  the  next 
machine  to  Z  could  be  designated  as  AB  or  A  A,  the  next  AC  or  BB,  etc. 

Some  prefer  to  designate  the  machine  by  the  initial  letters  of  its 
name.  This  plan  obviously  has  some  advantages,  but  it  has  also  the 
disadvantage  that  the  second  design  of  any  class,  and  each  subsequent 
design,  must  take  a  sub-letter.  In  designing  a  series  of  upright  drills,  for 
instance,  if  the  first  size  be  marked  UD,  subsequent  sizes  would  be 
marked  UDa,  UDb,  etc. 

Some  manufacturers  give  each  machine  a  number  in  addition  to  its 
letter.  In  this  system  the  first  machine  of  a  given  design  would  be  A  1,  the 
second  A  2,  etc.  Whether  the  machine  number  appears  on  the  name-plate  of 
the  machine  or  not,  it  is  kept  in  the  factory,  and  the  number  of  machines 
of  a  certain  design  sold,  together  with  any  alterations,  are  noted  in  records 
kept  for  this  purpose.  As  indicated,  the  machine  letter  is  marked  on 


THE  INTERCHANGEABLE  SYSTEM  OF  MANUFACTURE        505 

the  detail  in  connection  with  the  detail  number  or  symbol;  but  the 
machine  number  (except  in  such  aystems  as  use  numbers  to  symbolize 
the  different  designs  of  machines)^  should  not  appear  on  any  other  part 
than  the  name-plate  casting. 

A  system  of  machine  nomenclature  is  valuable  not  only  in  ordering 
duplicate  parts,  but  in  distinguishing  the  castings  and  patterns  in  the 
shop.  In  cases  where  there  are  many  kinds  of  patterns  this  greatly 
facilitates  the  work  in  the  shops. 


CHAPTER  XXXI 
MISCELLANEOUS  MACHINE-SHOP  METHODS 

Lapping. — Lapping  is  a  kind  of  grinding,  and  it  is  applied  to  such 
work  as  requires  a  higher  degree  of  refinement  than  is  possible  by  the 
ordinary  process  of  the  universal  grinder.  We  sometimes  lap  a  machine- 
shaft  which  is  required  to  run  at  an  extremely  high  speed,  say  6000 
revolutions  per  minute.  Other  machine  details  may  be  lapped  when 
an  exceptionally  high  degree  of  refinement  is  required,  but  the  process 
is  more  commonly  applied  to  measuring-tools,  such  as  the  collar-  and 
plug-gages,  etc.  The  process  of  lapping  the  collar-  and  plug-gages  will 
illustrate  the  general  principle.  Having  ground  the  collar,  it  is  next 
placed  on  a  freely  fitting  shaft  and  supported  on  the  lathe-centers  as  in 
turning.  We  now  apply  oil  and  emery-dust  to  the  shaft,  and,  causing 
the  latter  to  rapidly  revolve,  we  move  the  collar  back  and  forth  length- 
wise of  the  shaft  by  hand,  and  at  the  same  time  revolve  it  slowly.  Ihe 
effect  of  this  is  to  grind  out  the  slight  imperfections  left  by  the  universal 
grinder.  The  plug  is  lapped  in  the  same  manner,  excepting  that  it 
revolves  in  the  lathe  the  same  as  a  shaft,  a  collar  being  used  for  the  lap. 

The  laps  above  described  are  of  the  simplest  and  cheapest  forms, 
namely,  a  plain  shaft  for  the  internal,  and  a  collar  for  the  external,  lap, 
and  both  are  made  of  cast  iron;  but  when  there  is  considerable  lapping 
to  be  done  it  pays  to  make  adjustable  laps.  For  internal  lapping  the 
adjustment  may  be  provided  by  cutting  a  narrow  slot  through  the  center 
of  the  shaft  and  using  a  headless  set-screw  to  expand  the  shaft.  This  set- 
screw  should  be  screwed  into  a  tapped  hole  in  one  section  of  the  shaft , 
its  point  pressing  against  the  other  section,  as  shown  in  Fig.  686.  The  slot 
should  stop  short  of  the  ends  of  the  shaft  an  inch  or  more,  leaving  the 
ends  solid.  For  external  lapping  the  lapping  collar  may  be  made  with 
a  slotted  lug  on  one  side  with  a  screw  in  the  lug  by  which  to  close  the 
collar  to  compensate  for  wear.  Fig.  687  shows  this  design. 

The  adjustable  laps  are  generally  made  with  lead  strips  extending 
lengthwise  of  the  lap.  These  strips  are  formed  by  pouring  melted  lead 

506 


MISCELLANEOUS    SHOP  METHODS 


507 


into  recesses  cut  in  the  lap,  the  lead  being  trimmed  down  to  the  surface 
of  the  lap.  The  object  of  the  lead  is  to  hold  the  emery,  which  becomes 
imbedded  in  the  lead.  Large  *o.r  long  laps  are  sometimes  made  by 
casting  a  lead  sleeve  or  collar  on  a  tapering  shaft.  This  sleeve  is  turned 
in  the  lathe  the  required  she,  and  when  worn  too  small  the  sleeve  is 
enlarged  by  driving  in  the  tapering  shaft.  A  groove  is  cut  lengthwise 
of  the  shaft.  This  groove  is  filled  with  lead  in  casting,  and  serves  as  a 
key  to  keep  the  sleeve  from  turning  on  the  shaft.  This  form  is  shown  in 


A,B,C,D=Lead 


FIG.  686. 


FIG.  687. 


Internal  Lead  Lap 
FIG.  688. 


Fig.  688.  Great  care  is  necessary  in  lapping  holes  to  prevent  the  lap 
making  the  hole  large  at  the  ends.  To  avoid  this  the  laps  are  sometimes 
made  slightly  convex. 

Grinding  Valves,  Joints,  etc. — Lapping  is  sometimes  used  in  making 
steam-  and  water-tight  joints,  but  in  such  cases  it  is  generally  called 
grinding.  Conical  valves,  flat-seated  valves,  etc.,  are  sometimes  fitted 
in  this  way.  The  process,  however,  is  not  so  much  used  in  this  line 
of  work  as  formerly.  A  machine  has  been  designed  which  does  this 
work  so  accurately  as  to  obviate  in  many  cases  the  necessity  for  the 
grinding. 

If  a  lapped  or  ground  joint  is  wanted  in  such  a  case  as  the  cylinder- 
head  on  a  steam-engine,  the  head  is  so  turned  as  to  leave  a  narrow 
circular  strip  for  grinding.  This  strip  is  first  scraped  as  nearly  true  as 
practicable,  and  then  emery  and  oil  are  applied  and  the  head  rotated 
backward  and  forward  until  the  surface  is  true.  During  this  grinding 
process  the  surface  should  be  frequently  examined,  and  care  should  be 
taken  to  avoid  getting  emery  on  the  low  spots. 


508  MACHINE-SHOP  TOOLS  AND  METHODS 

Shrink  -fits.  —  The  ordinary  method  of  securing  gears,  pulleys,  etc., 
to  shafts  is  by  means  of  key,  set-screw,  or  pin.  In  some  lines  of  machinery, 
however,  shrink-fits  and  force-fits  are  used.  The  tires  of  locomotive 
driving-wheels  are  shrunk  on,  and  the  common  car-wheels  are  usually 
forced  on  by  hydraulic  pressure.  The  tire  is  usually  turned  about  .001" 
per  inch  of  diameter  smaller  than  the  driving-wheel  proper.  (The 
latter  is  called  wheel-center.)  The  tire  is  then  expanded  by  heat  until 
large  enough  to  slip  over  the  wheel-center.  Having  properly  placed 
the  tire  on  the  wheel-center  it  is  next  cooled  off,  which  causes  it  to 
contract  and  tightly  grip  the  wheel-  center.  The  allowance  of  .001" 
per  inch  of  diameter,  although  slightly  less  than  allowed  by  some  rail- 
roads, is  a  very  convenient  and  doubtless  a  very  .satisfactory  rule  for 
tires  as  well  as  other  large  work,  but  for  diameters  12"  and  less  the 

.         ,    Diameter  of  shaft  . 

formula  -       —  Tn/SfT"      "  +  .001"  is  proposed  as  likely  to   give  better 


results. 

The  following  table  of  shrinkage  allowances  was  copied  from  one 
of  the  leading  mechanical  journals  (name  of  journal  lost)  : 

Size  in  Inches.  Allowance  for  Shrinkage. 

2  inches  and  under  1/wo  inch  or  less 

2  to  4  Vioo 

4  to  6  Y64 

6  tO  9  3/128 

9  tO   12  1/32 

12  tO   18  3/64 

18  to  24  i/2o 

24  to  35  Vis 

35  to  45  Vi6 

45  to  55  Yu 

55  to  65  Yi2 

This  table  gives  a  greater  allowance  than  the  formula,  but  such 
practice  is  doubtful.  Any  rule  that  may  be  adopted  should  be  used 
with  discrimination;  for  it  is  obvious  that  a  light  cast-iron  ring  will  not 
stand  the  strain  that  might  be  safe  for  a  heavy  steel  ring.  The  hole  is 
usually  made  standard  size,  the  allowance  being  made  on  the  shaft. 

In  shrinking  on  such  work  as  collars  and  shaft-  couplings,  the  envelop- 
ing piece  should  be  heated  from  the  outside  rather  than  through  the 
hole.  If  heated  from  the  inside  first  the  hole  will,  in  some  cases,  be 
made  temporarily  smaller,  and  the  shaft  will  not  at  first  enter.  Or  if 
the  shaft  be  forced  in,  it  is  likely  to  be  an  unsatisfactory  fit  later  when 
the  heat  has  uniformly  penetrated  the  outside  piece  and  expanded  it. 


MISCELLANEOUS   SHOP  METHODS  509 

It  is  important  to  cool  the  enveloping  piece  as  quickly  as  practi- 
cable, or  keep  the  shaft  cool;  ptherwise  the  heat  may  penetrate  and 
expand  the  shaft.  This  might  stretch  the  outside  piece.  If  for  any 
reason  it  is  necessary  to"remove  the  shaft  from  some  piece  which  has 
been  shrunk  on  it,  great  care  is  necessary  to  keep  the  shaft  cool  while 
heating  the  outside  piece.  If  both  are  heated  both  will  be  expanded. 

Bands  are  sometimes  shrunk  on  hubs  of  pulleys,  gears,  etc.,  to 
strengthen  them.  When  both  surfaces  are  smooth  and  true  the 
allowance  made  by  the  formula  is  about  right.  But  it  often  happens 
that  neither  band  nor  hub  is  machined.  In  such  a  case  we  cannot 
measure  so  accurately,  but  by  measuring  the  hub  in  different  places 
and  taking  as  nearly  as  possible  the  average  diameter  we  need  not  err 
greatly  from  the  allowance  recommended. 

Force -fits. — By  force-fit  is  meant  the  fit  made  by  forcing  a  shaft 
into  a  wheel  or  other  part  by  hydraulic  or  other  pressure.  The  data 
respecting  force-fits  is  not  so  satisfactory  as  that  relating  to  shrink- 
fits.  The  tightness  of  the  fit  is  usually  designated  by  the  pressure 
required  to  force  the  shaft  into  the  hole.  In  the  best  practice  the  pres- 
sure for  this  purpose  varies  between  six  and  nine  tons  per  inch  of  diam- 
eter, according  to  the  smoothness  or  roughness  of  shaft  and  hole.  If, 
for  instance,  in  forcing  an  axle  into  a  car-wheel,  the  pressure  indicated 
on  the  gage  is  considerably  less  than  the  minimum  above  given,  the 
car-wheel  is  rejected;  if  much  greater  than  the  maximum,  the  axle 
is  taken  to  the  lathe  and  reduced  in  diameter. 

The  allowance  for  the  force-fit  is  seldom  indicated  in  terms  of  the 
diameter.  The  amount  is  in  many  factories  left  to  the  judgment  of 
the  mechanic.  If  required  to  give  the  allowance  in  terms  of  the  shaft 

,         ,     Diameter  of  shaft      m*-..  lr>,, 

diameter,  the  formula  -  -+.0015"  up  to   12"  would  be 

not  far  from  correct,  assuming  smooth  surfaces  for  both  shaft  and  hole, 
and  hub  about  twice  the  diameter  of  shaft. 

In  some  shops  the  shaft  is  turned  rough,  forming  a  kind  of  thread. 
With  this  method  the  shaft  does  not  need  to  be  so  exact  as  to  diameter, 
as  the  rough  surface  when  but  slightly  excessive  in  diameter  will  be 
cut  away  by  the  enveloping  piece  while  it  is  being  pressed  on  the  shaft. 

In  making  shrink-  or  force-fits,  especially  if  the  enveloping  piece 
be  frail,  care  should  be  taken  that  the  stress  does  not  exceed  the  elas- 
tic limit  of  the  outside  part.  But  considering  that  both  shaft  and 
enveloping  piece  are  compressed  to  a  slight  extent,  it  is  believed  that 
the  allowance  recommended  in  the  preceding  formulas  will  give  satis- 


510  MACHINE-SHOP  TOOLS  AND  METHODS 

factory  results  when  the  hub  conforms  to  the  above  proportions.  If 
the  hub  be  much  weaker,  the  constant  in  the  above  formula  for  force- 
fits  might  be  changed  to  .0005".  For  further  information  on  this  sub- 
ject, together  with  diagrams  of  allowances  for  driving-fits,  running-fits, 
and  limit-gages,  see  the  data-sheet  issued  in  connection  with  the  engineer- 
ing edition  of  "Machinery"  for  August,  1903,  and  "The  American 
Machinist"  for  August  6,  1903. 

Formulas  for  force-fits,  shrink-fits,  and  drive-fits,  given  in  the  above 
issue  of  "Machinery,"  are  as  follows: 

Force-fits,    ^  =  2D  +  .5; 

Shrink-fits, 

Drive-fits, 


where  A  =  allowance  in  thousandths  of  an  inch  and  D  =  nominal  diam- 
eter of  fit.  It  will  be  seen  that  the  formula  for  shrink-fits  agrees  very 
nearly  with  the  one  proposed  in  this  work;  but  the  formula  for  force- 
fits  gives  much  greater  values,  and  probably  subjects  the  enveloping 
part  to  a  considerable  initial  tension. 

The  article  in  "The  American  Machinist"  is  by  Mr.  John  Riddell. 
He  provides  for  four  different  cases,  varying  with  the  material  used  and 
the  class  of  work,  as  follows: 

Nominal  Diameter.  Minimum.  Maximum. 

2  in  .0005  .0015 

4"  .00075  .00275 

6"  .001  .0035 

8"  .001  .0045 

10'-'  .001  .00525 

12"  .001  .00575 

The  maximum  allowances  in  this  table  are  for  the  heaviest  force-fits 
and  also  for  shrink-fits.  It  will  be  noticed  that  there  is  a  wide  difference 
between  Mr.  RiddelPs  allowances  and  those  quoted  from  "Machinery." 
Different  writers  have  been  quoted  on  this  subject  to  emphasize  what 
was  indicated  above,  namely,  that  these  formulas  respecting  force-fits 
and  shrink-fits,  like  many  other  mechanical  formulas,  should  be  used 
with  judgment  and  discrimination. 


MISCELLANEOUS    SHOP  METHODS 


511 


Balance  Weight 


Machines  Used  in  Making  Force-fits. —  In  factories  where  a  great 
deal  of  this  kind  of  work  is  done  hydraulic  machines  are  used.  These 
are  furnished  with  gages  which  Register  the  amount  of  pressure.  When 
such  expensive  machines- cannot  be  afforded  a  screw-press  may  be  used 
for  the  purpose.  However,  the  screw-press  has  very  low  efficiency  and 
it  is  not  very  satisfactory  for  forcing  shafts  above,  say,  5". 

Balancing  Pulleys. — All  machine  rotating  parts  which  run  at  coii- 
siderable  speeds  should  be  balanced.  That  is  to  say,  the  weight  of  the 
material  of  which  the  rotating  piece  is  composed  should  be  distributed 
symmetrically  with  respect  to  the  axis  on  which  the  piece  revolves.  Take, 
for  instance,  a  common  pulley;  if 

the  rim  on  one  side  be  heavier  than  Balancing  Pulleys 

on  the  side  diametrically  opposite, 
the  centrifugal  force  will  be  greater 
on  the  heavy  side  and  this  will  tend 
to  cause  vibration  of  the  shaft. 

Pulleys  are  not  ordinarily  in  a 
balanced  condition  when  the  lathe 
work  is  finished.  The  method  of 
balancing  them  for  ordinary  speed 
is  as  follows :  Insert  a  closely  fit-  FIG.  689. 

ting  arbor  in  the  pulley  and  place  the 

whole  upon  two  straight  strips  of  metal  which  have  been  carefully 
leveled  on  suitable  supports,  as  shown  in  Fig.  689.  When  thus  arranged 
the  arbor  will  roll  with  the  pulley  until  the  heavy  side  of  the  latter  stops  at 
the  bottom.  The  pulley  should  now  be  weighted  with  putty  or  clay  on 
the  inner  side  of  the  rim  until  it  will  stop  in  any  position.  Having 
marked  the  exact  point  where  the  putty  was  placed,  a  hole  about  Vie" 
diameter  is  drilled  for  the  rivet  at  that  point  and  then  countersunk 
on  the  outside  of  the  rim. 

For  the  balancing  weights  button-shaped  blocks  of  iron  of  different 
sizes  are  used.  One  of  these  equaling  in  weight  the  putty  is  riveted  to 
the  pulley,  the  rivet  being  filed  flush  with  the  outside  of  the  rim.  If 
the  pulley  is  to  be  held  by  set-screws,  these  should  be  in  place  before  the 
pulley  is  balanced.  If  it  is  to  be  keyed,  an  arbor  with  key-seat  and  key 
should  be  used  in  balancing,  or  the  difference  made  by  keyway  and  key 
should  be  estimated. 

A  pulley  balanced  by  the  above  method  is  said  to  be  in  "  standing 
balance,"  and  this  is  the  method  used  in  all  but  exceptional  cases.  A 
little  consideration,  however,  will  show  that  it  is  not  exact;  for  while  the 


512  MACHINE-SHOP  TOOLS  AND  METHODS 

method  enables  us  to  find  the  heavy  side  of  the  pulley,  it  does  not  indicate 
the  position  of  the  heavy  part  lengthwise  the  pulley.  For  pulleys  more 
than,  say,  12"  face,  or  length,  and  running  above  2000  revolutions  per 
minute,  it  may  be  necessary  to  locate  the  counterbalance  in  the  same 
plane  at  right  angles  to  the  arbor  axis  as  the  heavy  part.  There  is 
no  simple  method  of  determining  this  position.  The  Defiance  Machine 
Company,  of  Defiance,  Ohio,  make  a  machine  for  the  purpose,  but 
persons  who  cannot  afford  to  purchase  such  a  machine  use  various 
cut-and-try  methods.  Such  methods  may  be  best  explained  in  the 
classroom.  Pulleys  are  sometimes  balanced  more  accurately  by  turning 
the  hub  on  the  outside,  and  rim  on  inside  as  well  as  outside. 

Balancing  Cutter-heads. — Cutter-heads  (for  wood-working  machinery) 
which  run  at  high  velocities  usually  require  to  be  balanced  with  extreme 
accuracy.  Not  only  are  the  heads  machined  very  carefully,  but  bolts, 
washers,  and  knives  on  opposite  sides  are  delicately  weighed  to  insure  an 
equal  distribution  of  centrifugal  force.  When  complete  the  cutter-head 
and  all  its  attachments  must  be  given  a  final  test,  and  if  found  out  of 
balance  the  correction  may  be  made  by  drilling  or  otherwise  cutting 
metal  from  the  head. 

Balancing  Emery-wheels. — In  balancing  an  emery-wheel,  the  nuts, 
collars,  etc.,  should  be  truly  turned  in  the  lathe.  The  emery-wheel  and 
arbor  complete  should  then  be  tested,  and  if  found  out  of  balance  the 
correction  may  be  made  by  drilling  into  the  collars.  If  but  slightly  out 
of  balance,  holes  cut  in  the  gaskets  between  collar  and  emery-wheel  will 
answer  the  purpose.  Some  manufacturers  make  flat-bottom  holes  on 
the  inner  side  of  the  collar-flanges.  When  so  made  the  correction  for 
balancing  may  be  made  by  filling  in  these  holes  on  the  light  side. 

It  may  be  remarked  in  this  connection  that  an  improperly  mounted 
emery-wheel  is  a  dangerous  piece  of  machinery.  The  wheel  should  not 
be  forced  on  the  arbor,  but  should  fit  freely,  and  rubber  or  other  soft 
gaskets  should  be  placed  between  the  wheel  and  the  collars  on  both  sides. 
The  wheel  should  generally  run  not  faster  than  recommended  by  the  manu- 
facturer. As  a  further  precaution  wheels  of  greater  diameter  than  about 
51/ ' _"  should  be  covered  with  suitable  guards. 


CHAPTER  XXXII 

TABLES*  RECIPES,  ETC. 

>: 

TABLE  No.  1. 

THE   PRINCIPAL  WIRE-GAGES   USED    IN  THE   UNITED   STATES. 


Number 
of  Wire- 
gage. 

American 
or  Brown 
&  Sharpe. 

Birming- 
ham or 
Stubs' 
Wire. 

Washburn 
&  Moen 
Mfg.  Co., 
Worcester, 
Mass. 

Imperial 
Wire- 
gage. 

Stubs' 
Steel 
Wire. 

U.  S.  Stand- 
ard for  Plate. 

Number 
of  Wire- 
gage. 

OOOCOO 

.464 

.  46875 

000000 

00000 

.432 

.4375 

00000 

0000 

.46 

.454 

.  3938 

.400 

40625 

0000 

000 

.40964 

.425 

.3625 

.372 

.375 

000 

00 

.3648 

.38 

.3310 

.348 

.34375 

00 

0 

.32486 

.34 

.3065 

.324 

.3125 

0 

1 

.2893 

.3 

.2830 

.300 

.227 

.28125 

1 

2 

.25763 

.284 

.2625 

.276 

.219 

.265625 

2 

3 

.22942 

.259 

.2437 

.252 

.212 

.25 

3 

4 

.20431 

.238 

.2253 

.232 

.207 

.234375 

4 

5 

.18194 

.22 

.2070 

.212 

.204 

.21875 

5 

6 

.  16202 

.203 

.1920 

.192 

.201 

.203125 

6 

7 

.  14428 

.18 

.1770 

.176 

.199 

.1875 

7 

8 

.  12849 

.165 

.1620 

.160 

.197 

.171875 

8 

9 

.11443 

.148 

.1483 

.144 

.194 

.15625 

9 

10 

.10189 

.134 

.1350 

.128 

.191 

.  140625 

10 

11 

.090742 

.12 

.1205 

.116 

.188 

.125 

11 

12 

.080808 

.109 

.1055 

.104 

.185 

.  109375 

12 

13 

.071961 

.095 

.0915 

.092 

.182 

.09375 

13 

14 

.064084 

.083 

.0800 

.080 

.180 

.078125 

14 

15 

.057068 

.072 

.0720 

.072 

.178 

.0703125 

15 

16 

.05082 

.065 

.0625 

.064 

.175 

.0625 

16 

17 

.045257 

.058 

.0510 

.056 

.172 

.05625 

17 

18 

.040303 

.049 

.0475 

.048 

.168 

.05 

18 

19 

.03589 

.042 

.0410 

.040 

.164 

.04375 

19 

20 

.031961 

.035 

.0348 

.036 

.161 

.0375 

20 

21 

.028462 

.032 

.03175 

.032 

.157 

.034375 

21 

22 

.025347 

.028 

.0286 

.028 

.155 

.03125 

22 

23 

.022571 

.025 

.0258 

.024 

.153 

.028125 

23 

24 

.0201 

.022 

.0230 

.022 

.151 

.025 

24 

25 

.0179 

.02 

.0204 

.020 

.148 

.021875 

25 

26 

.01594 

.018 

.0181 

.018 

.146 

.01875 

26 

27 

.014195 

.016 

.0173 

.0164 

.143 

.0171875 

27 

28 

.012641 

.014 

.0162 

.0149 

.139 

.015625 

28 

29 

.011257 

.013 

.0150 

.0136 

.134 

.0140625 

29 

30 

.010025 

.012 

.0140 

.0124 

.127 

.0125 

30 

31 

.008928 

.01 

.0132 

.0116 

.120 

.0109375 

31 

32 

.00795 

.009 

.0128 

.0108 

.115 

.01015625 

32 

33 

.00708 

.008 

.0118 

.0100 

.112 

.009375 

33 

34 

.006304 

.007 

.0104 

.0092 

.110 

.00859375 

34 

3"> 

.005614 

.005 

.0095 

.0084 

.108 

.0078125 

35 

3  > 

.005 

.004 

.0090 

.0076 

.106 

.00703125 

36 

37 

.004453 

.0068 

.103 

.006640625 

37 

38 

.  003965 

.0060 

.101 

.00625 

38 

39 

.003531 

.0052 

099 

.  \j\s\s 

39 

40 

.003144 

.0048 

.097 

40 

513 


514 


MACHINE-SHOP  TOOLS  AND  METHODS 


TABLE  No.  2. 

GAGE  NUMBERS  AND  DIAMETERS   FOR   TWIST-DRILLS. 


Gage 
Number. 

Diameter, 
Inches. 

Gage 
Number. 

Diameter, 
Inches. 

Gage 
Number. 

Diameter, 
Inches. 

Gage 
Number, 

Diameter, 
Inches. 

1 

.2280 

21 

.1590 

41 

.0960 

61 

.0390 

2 

.2210 

22 

.1570 

42 

.0935 

62 

.0380 

3 

.2130 

23 

.1540 

43 

.0890 

63 

.0370 

4 

.2090 

24 

.1520 

44 

.0860 

64 

.0360 

5 

.2055 

25 

.1495 

45 

.0820 

65 

.0350 

6 

.2040 

26 

.1470 

46 

.0810 

66 

.0330 

7 

.2010 

27 

.1440 

47 

.0785 

67 

.0320 

8 

.1990 

28 

.1405 

48 

.0760 

68 

.0310 

9 

.1960 

29 

.1360 

49 

.0730 

69 

.02925 

10 

.1935 

30 

.1285 

£0 

.0700 

70 

.0280 

11 

.1910 

31 

.1200 

51 

.0670 

71 

.0260 

12 

.1890 

32 

.1160 

52 

.0635 

72 

.0250 

13 

.1850 

33 

.1130 

53 

.0595 

73 

.0240 

14 

.1820 

34 

.1110 

54 

.0550 

74 

.0225 

15 

.1800 

35 

.1100 

55 

.0520 

75 

.0210 

16 

.1770 

36 

.1065 

56 

.0465 

76 

.0200 

17 

.1730 

37 

.1040 

57 

.0430 

77 

.0180 

18 

.1695 

38 

.1015 

58 

.0420 

78 

.0160 

19 

.1660 

39 

.0995 

59 

.0410 

79 

.0145 

20 

.1610 

40 

.0980 

60 

.0400 

80 

.0135 

TABLES,  RECIPES,  ETC. 


515 


TABLE  No.  3. 

GAGE    NUMBERS    AND    DIAMETERS    FOR    WOOD    AND    MACHINE-SCREWS. 


Number 
of  Screw. 

Diameter, 
Inches. 

Number 
of  Screw 

Diameter, 
Inches. 

Number 
of  Screw. 

Diameter, 
Inches. 

Number 
of  Screw. 

Diameter, 
Inches. 

000 

00 
0 

1 

2 

.03152 
.04468 
.05784 
.07100 
.08416 

12 
13 
14 
15 
16 

.21576 
.22892 
.24208 
.25524 
.26840 

25 
26 
27 

28 
29 

.38684 
.40000 
.41316 
.42632 
.43948 

38 
39 
40 
41 
42 

.55792 
.57108 
.58424 
.59740 
.61056 

3 

4 
5 

6 

7 

.09732 
.11048 
.  12364 
.  13680 
.  14996 

17 
18 
19 
20 
21 

.28156 
.29472 
.30788 
.32104 
.33420 

30 
31 
32 
33 
34 

.45264 
.46580 
.47896 
.49212 
.50528 

43 

44 
45 
46 
47 

.62372 
.63688 
.65004 
.66320 
.67636 

8 
9 
10 
11 

.16312 
.  17628 
.  18944 
.20260 

22 
23 

24 

.34736 
.36052 
.37368 

35 
36 
37 

.51844 
.53160 
.54476 

48 
49 
50 

.68952 
.70268 
.71584 

Small  screws,  especially  sizes  below  \",  are  made  in  either  "fractional"  or 
screw-gage  diameters.  The  United  States  standard  is  generally  disregarded  in  small 
screws,  with  respect  to  both  the  pitch  and  the  shape. 

The  diameters  corresponding  to  the  tap  numbers  in  Table  No.  5  are  the  same 
as  the  diameters  given  for  the  "No.  of  screw"  in  Table  No.  3.  The  drill  numbers 
given  in  Tables  No.  4  and  No.  5  refer  to  Table  No  2.  The  latter  table  is  sometimes 
used  for  measuring  wire  also.  The  tap-drill  sizes  allow  what  is  considered  suffi- 
cient clearance  above  the  root  of  the  thread.  When  a  full  thread  is  required,  the 
diameter  of  the  drill  may  be  calculated  from  Table  No.  8  and  the  accompanying 
formula. 


516 


MACHINE-SHOP  TOOLS  AND  METHODS 


TABLE  No.  4. 

TAP-DRILLS    FOR    V   THREADS. 


Diameter  of 

Threads 

Drill 

Diameter  of 

Threads 

Drill 

Tap,  Inches. 

per  Inch. 

Number. 

Tap,  Inches. 

per  Inch. 

Number. 

'    48 

50 

30 

33 

, 

52 

50 

g 

32 

32 

^J 

54 

49 

32 

36 

31 

56 

49 

40 

30 

32 

50 

32 

30 

_ 

36 

49 

36 

29 

3T 

40 

47 

64 

40 

28 

48 

44 

36 

43 

24 

29 

i 

40 
42 

42 
41 

A 

28 
30 

28 

27 

48 

39 

32 

26 

30 

41 

24 

18 

32 

40 

28 

17 

TT 

36 

37 

A 

30 

16 

40 

34 

32 

15 

TABLES,  RECIPES,  ETC. 


517 


TABLE  No.  5. 

TAP-DRILLS    FOR    MACHINE-SCREW   TAPS. 


Number 
of  Tap. 

Threads 
per  Inch. 

Drill 
Number. 

Number 
of  Tap. 

Threads 
per  Inch. 

Drill 
Number. 

2 

48 
56 
64 

48 
46 
45 

10 

24 

28 
30 
32 

26 
24 
23 
21 

3 

40 

48 
56 

48 
47 
45 

11 

24 
28 
30 

20 
19 
18 

4 

32 

36 
40 

45 
43 
42 

12 

20 
22 

24 

21 
19 
19 

5 

30 
32 
36 

40 

41 
40 
38 
36 

13 

20 
24 

17 
15 

14 

20 
22 
24 

14 
13 
11 

6 

30 
32 

36 
40 

39 
37 
35 
33 

15 

18 
20 
24 

12 
10 

7 

7 

28 
30 
32 

32 
31 
30 

16 

16 
18 
20 
24 

10 

7 
5 

1 

8 

24 
30 
32 

31 
30 
29 

17 

16 
18 
20 

7 
4 
2 

9 

24 
28 
30 
32 

29 
27 
26 
24 

18 

16 
18 

2 
1 

518 


MACHINE-SHOP  TOOLS  AND  METHODS 


TABLE  No.  6. 

TAP-DRILL  SIZES    FOR   U.  S.    STANDARD    THREAD. 


Diameter  of 
Tap,  Inches. 

Number  of 
Threads  per 
Inch. 

Diameter  at 
Root,  Inches. 

Diameter  of 
Drill,  Inches. 

Difference  between 
Drill  Size  and 
Root  of  Thread. 

£ 

20 

.185 

U 

.018 

^ 

18 

.2403 

.010 

| 

16 

.2936 

A 

.0189 

ft 

14 

.3447 

H 

.0146 

£ 

13 

.4001 

fi 

.0218 

1$> 

12 

.4542 

& 

.0145 

| 

11 

.5069 

H 

.0244 

I 

10 

.6201 

ft 

.0201 

f 

9 

.7307 

f 

.0193 

1 

8 

.8376 

H 

.0218 

If 

7 

.9394 

& 

.0294 

11 

7 
6 

1.0644 
1.1585 

J* 

i* 

.0294 
.0290 

If 

6 

1.2835 

i* 

.0290 

If 

5* 

1.3888 

Mi 

.0321 

1! 

5 
5 

1.4902 
1.6152 

IH 
i» 

.0411 
.0411 

2 

*i 

1.7113 

t! 

.0387 

TABLE  No.  7. 

TAP-DRILL   SIZES    FOR    PIPE-TAPS. 


Diameter  of 
Tap,  Inches. 

Number  of 
Threads  per 
Inch. 

Diameter  of 
Drill,  Inches. 

Diameter  of 
Tap,  Inches. 

Number  of 
Threads  per 
Inch. 

Diameter  of 
Drill,  Inches. 

27 

H 

H 

ill 

IJ 

18 

A 

ii 

ul 

Iff 

18 

H 

2 

ii| 

2& 

14 

if 

2* 

8 

2f 

14 

H 

3 

8 

3* 

11* 

IA 

Reamers  should  be  used  for  the  larger  pipe-taps. 


TABLES,  RECIPES,  ETC. 


519 


TABLE  No.  8. 

CONSTANTS    FOR   FINDING   DIAMETER   AT    BOTTOM   OF   THREAD. 
(Used  by  permissioA  of  the  Pratt  and  Whitney  Co.) 


Threads 

U.  S.  Standard 

~"V"  Thread 

Threads 

U.  S.  Standard 

"V"  Thread 

per  Inch. 

Constant. 

Constant. 

per  Inch. 

Constant. 

Constant. 

64 

.02029 

.02706 

16 

.08118 

.  1082~> 

60 

.02165 

.02887 

14 

.09278 

.  12357 

56 

.02319 

.03093 

13 

.09992 

.  13323 

50 

.02598 

.03464 

12 

.10825 

.14433 

48 

.02706 

.03608 

11 

.11809 

.  15745 

44 

.02952 

.03936 

10 

.12990 

.17320 

40 

.03247 

.04330 

9 

.14433 

.  19244 

36 

.03608 

.04811 

8 

.16237 

.21650 

32 

.04059 

.05412 

7 

.  18555 

.24742 

30 

.04330 

.05773 

6 

.21650 

.28866 

28 

.04639 

.06185 

5i 

.23618 

.31490 

26 

.04996 

.06661 

5 

.25980 

.34650 

24 

.05412 

.07216 

41 

.28866 

.38488 

22 

.05904 

.07872 

4 

.32475 

.43300 

20 

.06495 

.08660 

3$ 

.37114 

.49485 

18 

.07216 

.09622 

3 

.43333 

.57733 

C=  constant  for  number  of  threads  per  inch; 
D=  outside  diameter; 
Z)'=  diameter  at  bottom  of  thread. 

D'=D-C. 

EXAMPLE. — Given  outside  diameter  of  U.  S.  standard  screw-thread,  2  inches; 
4J  threads  per  inch;  find  diameter  at  bottom  of  thread.  D=2  inches;  for  4£ 
threads  U.  S.  standard,  constant,  C  =  .2886;  then  diameter  at  bottom  of  thread, 
D'  =2 -.2886  =  1.7114  inches. 


A   FEW   USEFUL   RECIPES   AND    FACTS. 
(Nos.  1,  2,  3,  4,  6,  and  9  are  used  by  permission  of  Morse  Twist  Drill  and  Machine  Co.) 

1.  To  Harden  Cast  Iron. — Many  times  it  is  very  convenient  to  make  an  article 
of  cast  iron  that  needs  to  be  finished,  and  which  should  be  very  hard.     Cast  iron 
can  be  hardened  as  easily  as  steel,  and  to  such  a  degree  of  hardness  that  a  file  will 
not  touch  it.     Take  one-half  pint  vitriol,  one  peck  common  salt,  one-half  pound 
saltpetre,  two  pounds  alum,  one-quarter  pound  prussiate  potash,  one-quarter  pound 
cyanide  potash;   dissolve  in  ten  gallons  of  soft  water.     Be  sure  that  all  the  articles 
are  dissolved.     Heat  the  iron  to  a  cherry  red,  and  dip  it  in  the  solution.     If  the 
article  needs  to  be  very  hard,  heat  and  dip  the  second  and  even  the  third  time. 

2.  Annealing  Cast  Iron. — To  anneal  cast  iron,  heat  it  in  a  slow  charcoal-fire 
to  a  dull-red  heat;   then  cover  it  over  about  two  inches  with  fine  charcoal;   then 


520  MACHINE-SHOP  TOOLS  AND  METHODS 

cover  with  ashes.  Let  it  lay  until  cold.  Hard  cast  iron  can  be  softened  enough  in 
this  way  to  be  filed  or  drilled.  This  process  will  be  exceedingly  useful  to  iron 
founders,  as  by  this  means  there  will  be  a  great  saving  of  expense  in  making  new 
patterns. 

3.  To  make  a  Casting  of  Precisely  the  same  Size  of  a  Broken  Casting  without 
the  Original  Patterns. — Put  the  pieces  of  broken  casting  together  and  mould  them, 
and  cast  from  this  mould.     Then  anneal  it  as  above  described;    it  will  expand  to 
the  original  size  of  the  pattern,  and  there  remain  in  that  expanded  state. 

4.  How  to  Anneal  Brass  or  Copper. — In  working  brass  and  copper,  it  will  be- 
come hard,  and  if  hammered  to  any  great  extent  will  split.     To  prevent  cracking 
or  splitting,  the  piece  must  be  heated  to  a  dull-red  heat  and  plunged  in  cold  water; 
this  will  soften  it  so  it  can  be  worked  easily.     Be  careful  not  to  heat  brass  too  hot, 
or  it  will  fall  to  pieces.     The  piece  must  be  annealed  frequently  during  the  process 
of  hammering. 

5.  Case-hardening. — Steel,  wrought  iron,  etc.,  may  be  case-hardened  as  fol- 
lows:  Polish  the  piece,  heat  to  bright  red,  and  rub  with  prussiate  of  potash.     Cool 
the  article  in  air  to  a  dull  red  and  then  immerse  in  water. 

6.  Weight  of  Castings. — If  you  have  a  pattern  made  of  soft  pine,  put  together 
without  nails;    an  iron  casting  made  from  it  will  weigh  sixteen  pounds  to  every 
pound  of  the  pattern.     If  the  casting  is  of  brass,  it  will  weigh  eighteen  pounds  to 
every  pound  of  the  pattern. 

7.  A  cubic  inch  of  cast  iron  weighs  .2607  pound;    wrought  iron  (bars),  .2817 
pound;    steel  (cast)  .2839  pound;    brass  (cast)  .2930  pound;    brass  (rolled)  .2972 
pound. 

8.  Determining   Diameters  of    Round  Stock  for  Hexagon-  and   Square-head 
Bolts. — For  hexagon,  the  distance  across  the  flats  divided  by  .866=  diameter  of 
stock.     For  square-head  bolts,  the  distance  across  flats  divided  by  .7071  =  diame- 
ter of  stock. 

9.  To  Sharpen  Reamers. — Hand  reamers,  when  dull  through  wear,  should  be 
stoned  first  on  the  face  of  the  flutes  then  on  top  of  the  flutes.     The  stone  should  be 
always  held  perfectly  flat  with  the  face  and  clearance  that  the  original  shape  of 
the  flutes  may  be  preserved.     End-cutting  reamers  should  be  first  turned  on  cen- 
ters with  a  wheel,  and  then  recleared  to  insure  reaming  a  hole  the  same  size  of  reamer. 


QUESTIONS   ON  THE  TEXT 


CHAPTER  I 

1.  What  is  the  value  of  the  English  yard  in  terms  of  the  meter? 

2.  What  is  the  difference  between  common  calipers  and  thread-calipers'. 

3.  In  fitting  a  shaft  to  a  gear  or  pulley  what  precautions  are  necessar-.    in 
adjusting  the  calipers? 

4.  What  is  a  Vernier  caliper? 

5.  What  two  systems  of  graduation  are  used  for  machine-shop  Ver,  der 
calipers? 

6.  Give    brief  descriptions   of   common   micrometer-calipers   and   scr>jw- 
thread  micrometer-calipers.     How  would  you  adjust  the  former  to  .-60%]!"? 
In  using  the  latter  to  measure  a  U.  S.  standard  screw,  what  value  must  be 
added  to  the  reading  of  the  instrument  in  order  to  obtain  the  outside  diameter 
of  the  screw?    What  value  must  be  added  to  obtain  the  outside  diameter  of 
the  V  thread? 

7.  Describe  an  inside  micrometer-gage,  a  micrometer  depth-gage. 

8.  Describe  a  method  of  compensating  for  errors  in  screws. 

9.  Describe  a  common  form  of  caliper-gage. 

10.  Describe  ordinary  collar-  and  plug-gages. 

11.  Describe  external-  and  internal-thread  gages. 

12.  What  is  the  purpose  of  a  limit-gage?     Describe  an  adjustable  limit- 
gage. 

13.  Sketch  and  describe  the  thread-  and  center-gage. 

14.  What  is  a  thread  pitch-gage? 

15.  What  is  a  templet? 

16.  Describe  the  common  surface-gage  and  tell  how  it  is  used.     What 
special  form  of  surface-gage  may  be  used  in  describing  circles,  and  how  is 
it  used? 

17.  Describe  a  common  wire-gage,  a  twist-drill  gage. 

18.  Describe  a  key-seat  rule. 

19.  Is  the  English  wire-gage  the  same  as  the  British  Imperial? 

20.  What  wire-gage   is  used  almost  exclusively  in  America  for  electrical 
purposes? 

21.  What  are  the  distinguishing  features  of  the  Edison  wire-gage? 

521 


522  MACHINE-SHOP  TOOLS  AND  METHODS 

22.  Is  there  a  standard  gage  in  the  U.  S.  for  the  diameters  of  wood-  and 
machine-screws  ? 

23.  What  precautions  are  necessary  in  ordering  wire  and  sheet  and  plate 
metal  to  avoid  delay? 

24.  What  is  the  most  accurate  and  reliable  method  of  measuring  and 
specifying  the  size  of  wire? 

25.  How  may  the  combination  square  be  used  for  measuring  tapers? 

CHAPTER  II 

26.  What  are  the  three  most  common  forms  of  hammer? 

27.  What  is  the  meaning  of  the  word  peen? 

28.  How  would   you   shape   a   crank-pin,  or  any  large  pin,  to  facilitate 
riveting? 

29.  What  methods  are  used  for  straightening  shafts? 

30.  What  is  the  effect  of  machining  a  peened  surface? 

31.  Describe  two  methods  of  straightening  long  bars  of  cast  iron. 

32.  How  may  the  peening  principle  be  applied,  for  enlarging  piston-rings? 
Explain  how  this  principle  may  be  used  in  fitting  connecting-rod  straps. 

CHAPTER  III 

33.  What  are  the  names  of  the  two  chisels  most  generally  used  in  the 
machine-shop? 

34.  To  'about   what   cutting   angle   should    a   chisel    be    ground   to    cut 
(a)  cast  iron,  (6)  steel,  (c)  Babbitt? 

35.  What  is  a  center-punch  and  for  what  purpose  is  it  used? 

36.  Describe  a  key-drift.     What  is  a  pin-drift? 

37.  In    chipping,   what    precaution   is    necessary   upon   approaching   the 
edge  of  the  work?    What   other   precaution  is  necessary  to  insure   smooth 
chipping? 

38.  What  precaution  is  necessary  in  grinding  chisels  and  other  tools  to 
prevent  drawing  the  temper? 

39.  In  general,  when  should  the  chisel  be  used  and  when  not? 

CHAPTER  IV 

40.  Into  what  three  general  classes  may  files  be  divided? 

41.  What   advantages   are    derived   from    making   a   file   with   a   convex 
surface? 

42.  Distinguish  between  cross-filing  and  draw-filing,  and  explain  the  pur- 
pose of  each. 

43.  What  is  a  safo-edge  file?    What  is  its  purpose? 

44.  What  is  meant  by  pinning,  and  how  may  it  be  partly  prevented? 

45.  What  files  are  most  commonly  used  in  the  machine-shop? 

46.  Describe  the  process  of  finishing  a  chipped  surface  by  filing. 


QUESTIONS  ON  THE  TEXT  523 

47.  How  may  very  broad  surfaces  be  filed? 

48.  How  may  curved  surfaces  be  filed  without  producing  flat  spots? 

49.  What  two  principles  are  ip  be  observed  in  filing  lathe  work? 

50.  What  source   of  ^danger  idr'to  be  guarded  against  in  filing  rotating 
work? 

51.  How  is  emery-cloth  applied  to  lathe  work  to  polish  it? 

52.  WThat  is  a  polishing-clamp? 

CHAPTER  V 

53.  What  is  a  surface-plate,  and  how  is  it  used? 

54.  Describe  a  typical  scraper. 

55.  How  may  chattering  of  a  scraper  be  obviated? 

56.  What    precautions    against  wasting   time    should   be    observed  when 
scraping  flat  surfaces? 

57.  What  form  of  scraper  may  be  used  in  fitting  a  bearing  to  its  shaft? 

58.  Describe  a  method  of  giving  an  ornamental  finish  with  the  scraper? 
With  emery-dust  and  a  pine  stick? 

59.  How  is  the  scraper  applied  to  work  in  the  lathe,  and  in  general,  for 
what  purpose? 

60.  What  is  a  "graver"  ? 

61.  Is  it  safe  to  use  files  and  scrapers  without  handles  on  lathe  work? 

CHAPTER  VI 

62.  Name  several  common  forms  of  vises. 

63.  How  is  provision  made  in  the  swivel-vise  for  swinging  work  in  a  hori- 
zontal plane? 

64.  How  may  a  vise  be  arranged  to  clamp  tapering  work? 

65.  How  is  a  vise  arranged  for  threading  pipes,  and  where  should  it  be 
placed? 

66.  Describe  the  hand-vise,  the  pin-vise. 

67.  What  are  the  advantages  in  having  vise-jaws  detachable? 

68.  What  materials  are  used  for  vise-clamps,  and  when  are  vise-clamps 
used? 

69.  Describe  a  good  design  of  hack-saw. 

CHAPTER  VII 

70.  What  is  the  definition  of  the  term  drill? 

71.  Describe  the  ratchet-drill;  for  what  is  it  used? 

72.  Describe  the  breast-drill. 

73.  Describe  the  Fifield  drilling  attachment,  and  tell  how  it  is  operated. 

74.  Describe  the  portable  drilling-machine,  and  tell  how  it  is  used. 

75.  What  are  the  essential  features  of  a  sensitive-drill.? 

76.  How  may  a  variable-speed  friction-drive   be  applied   to  a  sensitive- 
drii:? 


524  MACHINE-SHOP  TOOLS  AND  METHODS 

77.  Give  a  general  description  of  a  back-geared  drill. 

78.  What  is  the  principle  and  what  the  purpose  of  the  back  gears? 

79.  What  is  feed-gearing?  how  applied  to  the  drill? 

80.  What  is  an  automatic  stop,  and  what  advantage  has  it? 

81.  How  is  the  head  of  a  drill-press  usually  adjusted  as  to  height? 

82.  What    adjustments    are    provided    for    the    table    of  an  ordinary 
drill -press? 

83.  What  is  a  radial  drill?    What  advantages  has  it  over  the  common 
drill-press? 

84.  Give  a  general  description  of  the  main  driving  mechanism  of  the 
radial  drill  shown  in  Figs.  121  to  125. 

85.  Describe  the  feed-gearing  of  the  foregoing  machine. 

86.  Describe  the  depth-gage. 

87.  What  is  the  difference  between  the    universal   radial   drill   and   the 
plain  radial  drill? 

88.  What  is  the  object  of  the  tilting-table  shown  in  Fig.  132? 

89.  Give   general   descriptions  of  the   suspension-drill,  the  multispindle- 
drill,  and  the  turret-drill. 

90.  Explain  the    necessity  and   use    of   the   high-speed    attachment   for 
large  radial  drills. 

91.  How  is  a  hole  started  in  work  to  be  drilled? 

92.  Describe  a  method  of  holding  work  in  drilling-machines  (a)  by  bolts 
and  straps,  (6)  by  use  of  the  angle-plate,  (c)  by  use  of  the  drill-vise. 

93.  Describe  the  universal  vise  as  used  for  drilling. 

94.  How  are  V  blocks  used  in  connection  with  the  drilling-machine? 

95.  Describe  a  method  of  machining  hubs  in  the  drill. 

96.  What  is  the  most  accurate  method  of  adjusting  work  for  drilling? 

CHAPTER  VIII 

97.  Describe  the  twist-drill,  defining  longitudinal  clearance,  body  clear- 
ance, and  lip  clearance. 

98.  What  are  the  essentials  of  a  correctly  ground  drill? 

99.  What  is  the  effect  of  grinding  a  drill  eccentric? 

100.  How  does  the  farmer-drill  differ  from  the  twist-drill?    To  what  kind 
of  work  is  it  adapted? 

101.  Describe  a  flat-drill.     Under    what    circumstances  would  a  flat-drill 
be  used? 

102.  Describe   (a)   the  pin-drill   or  counterbore,   (b)   the  tit-drill,   (c)   the 
bottoming-drill. 

103.  What  is  the  purpose  of  the  oil-tube  drill? 

104.  Give  approximate  speed  formulas  for  drilling  (a)  machine  steel,  (b)  cast 
iron,  (c)  brass. 

105.  About  how  much  faster  may  drills  be  run  when  made  of  high-speed 
.steel  than  when  made  of  ordinary  tool  steel? 

106.  Give  approximate  rates  of  feed  for  drills. 


QUESTIONS  ON  THE  TEXT  525 

CHAPTER  IX 

107.  How  are  taper-shank  thrills  driven  in  the  drill-press?    What  is  the 
approximate  taper  of  the  "Morse  Standard"  ? 

108.  Describe  a  cheap  device  for  driving  broken-tang  drills. 

109.  How  are  straight-shank  drills  driven? 

110.  How  is  the  drill-socket  made  for  use  in  the  lathe?     By  what  other 
term  is  it  known? 

111.  How  may  the  taper-shank  drill  be  driven  by  a  drill-chuck? 

CHAPTER  X 

112.  What   is  the  purpose   of  a  reamer?     What  would  be  the  effect  of 
allowing  too  much  metal  for  the  reamer  to  cut? 

113.  Describe  the   solid   fluted  reamer.     What   is   the  object   of  making 
reamers  with  spiral  flutes? 

114.  What  is  the  essential  difference  between  the  rose  reamer  and  the 
fluted  reamer? 

115.  What  is  the  advantage  of  making  a  reamer  in  the  shell  form? 

116.  De:cribe    n  adjustable  reamer  with  detachable  blades.     What  is  th) 
object  of  the  adjustable  reamer? 

117.  Describe  a  good  form  of  chucking  reamer.     What  is  the  object  of  the 
chucking  reamer? 

118.  What  is  a  wood-bit  as  used  in  the  machine-shop? 

119.  Can  the  taper-reamer  be  used  in  the  rose  form? 

120.  What  is  the  object  of  notching  the  cutting  edges  of  a  reamer? 

121.  What  governs  the  number  of  cutting  edges  in  a  reamer? 

122.  What  is  the  effect  of  too  much  body  clearance  in  a  reamer?     What 
is  the  object  of  spacing  the  teeth  of  a  reamer  unequally? 

123.  For  what  purposes  may  square  reamers  be  used?     Describe  a  c  .eap 
method  of  making  square  reamers. 

124.  What  precautions  should  be  observed  in  hardening  reamers? 


CHAPTER  XI 

125.  What  are  the  distinguishing  features  between  the  hand-lathe  and  the 
engine-lathe? 

126.  Describe  the  principal  elements  in  connection  with  the  head-stock  of 
the  engine-lathe? 

127.  Describe  the  tail-stock. 

128.  Describe  the  thread-cutting  mechanism. 

129.  Is  the  feed-belt  reliable  for  thread-cutting? 

130.  Describe  the  feed  mechanism. 

131.  How  may  the  apron-gearing   and  lead-screw  be  designed  so  as  to 
admit  of  the  lead-screw  being  used  as  a  feed-rod? 


526  MACHINE-SHOP  TOOLS  AND  METHODS 

132.  Describe  the  screw-cutting  mechanism  of  the  lathe  shown  in  Figs.  218 
to  222. 

133.  Describe  the  operation  of  the  feed-clutches. 

134.  Explain  the  operation  of  the  apron-gearing  of  Fig.  223. 

135.  What   is  meant   by   "back-gear   ratio"?    How  is   this   ratio   com- 
puted? 

136.  Explain  the  principle  of  the  spur-gear  reversing  mechanism  as  illus- 
trated in  Fig.  225. 

137.  Describe  the  head-stock  gearing  shown  in  Figs.  227  and  228. 

138.  Explain  in  detail  (a)  the  raise-and-fall  rest,  (b)  the  plain  rest,  (c)  the 
compound  rest,  (d)  the  elevating  tool-rest,  (e)  the  open-side  tool-rest,  (/)  the 
three-tool  shafting-rest. 

139.  What  are  the  distinguishing  features  of  (a)  the  pulley-lathe,  (6)  the 
pit-lathe,  (c)  the  gap-lathe? 

140.  What  is  the  meaning  of  the  term  "swing"?     How  may  the  "swing" 
of  a  common  lathe  be  increased? 

141.  How  is  the  cutting  speed  of  a  lathe  designated?     In  general  what 
considerations  govern  the  cutting  speed?     How  many  revolutions  of  a  3-inch 
shaft  would  be  required  to  give  a  cutting  speed  of  35  ft.  per  minute?     What 
would  be  the  cutting  speed  of  a  3-inch  shaft  when  making  38.22  revolutions 
per  minute? 

142.  Name    some    of    the    brands    of    high-speed    steel    in    use.     About 
what    is    the    maximum    cutting    speed   when    using    the    best    high-speed 
steel? 

143.  What  considerations  govern  the  feed  in  lathe  work?     How  may  the 
rotary  measure  shown  in  Fig.  239  be  used  to  measure  cutting  speed? 

144.  What  is  the  advantage  of  a  hollow  spindle  in  a  lathe? 

145.  Describe  a  method  of  testing  the  alinement  of  a  lathe-spindle. 

CHAPTER  XII 

146.  What  are  the  distinguishing  features  of  the  turret-lathe? 

147.  Describe  the  plain  screw-machine. 

148.  Explain  the  chucking  principle  illustrated  in  Figs.  243  and  244. 

149.  Describe   a   method   of   making   filister-head    screws    in   the    screw- 
machine. 

150.  To  what  class  of  work  is  the  monitor  lathe  adapted? 

151.  Describe  the  characteristic  features  of  the  machines  shown  in  Figs.  248 
to  252. 

152.  What  is  the  principle  difference  between  the  machine  illustrated  in 
Fig.  252  and  that  shown  in  Fig.  259? 

153.  Briefly  describe  the  operations  illustrated  in  Figs.  261  to  266. 

154.  Give  three  different  methods  of  using  turrets  in  connection  with  the 
engine-lathe. 

155.  What  is  a  box  tool?    What  is  a  knee  tool?. 

156.  What  is  a  forming-tool,  and  to  what  class  of  work  is  it  adapted? 


QUESTIONS  ON  THE  TEXT  527 

CHAPTER  XIII 

157.  What  are  the  names  of  a  pommon  set  of  lathe-tools? 

158.  What  are  the  advantages  of  the  tool-holder  system  of  lathe- tools? 

159.  Describe  a  boring -system  in"  which  round  bars  with  inserted  cutters 
are  used.     What  advantages  has  this  system  as  compared  with  that  in  which 
forged  boring-tools  are  used? 

160.  Give  one  or  more  cases  in  which  a  multiple-edge  tool  may  be  used 
with  advanatge. 

161.  What  is  the  advantage  of  the  backward  offset  in  planer-tools?    How 
is  the  same  principle  employed  in  lathe-tools? 

162.  What  is  the  meaning  of  the  term  "rake"  as  applied  to  machine-shop 
tools?    What  is  the  effect  of  "rake"? 

163.  Does  changing  the  height  of  a  tool  change  its  angle  of  front  rake? 

164.  What  is  the  effect  on  the  side  clearance  of  changing  the  longitudinal 
feed? 

165.  How  do  tools  for  brass  differ  from  other  tools  with  respect  to  rake? 

166.  Why  do  planer-tools  require  less  rake  than  lathe-tools? 

167.  What  metals  are  machined  in  connection  with  lubricants? 

CHAPTER  XIV 

168.  What  is  the  correct  angle  for  the  point  of  a  lathe-center? 

169.  Why  are  hardened  centers  more  reliable  than  soft  centers? 

170.  Describe  a  machine  used  for  grinding  centers.      How  may  the  centers 
be  so  shaped  as  to  lessen  the  work  of  grinding? 

171.  What  precautions  in  using  lathe-centers  are   necessary  to    prevent 
eccentric  work? 

172.  About  what  are  suitable  proportions  for  work  centers?      Why  is  it 
important  to  drill  the  center  sufficiently  deep  to  give  clearance  to  the  point  of 
the  lathe-center? 

173.  Describe   the   tools   and  methods   employed   in   locating   centers   in 
work. 

174.  Describe  a  machine  designed  especially  for  centering.     Refer  back  to 
the  chapter  on  drilling-machines  and  explain  how  work  may  be  supported  in 
the  sensitive-drill  while  the  centers  are  being  drilled. 

CHAPTER  XV 

175.  What  is  the  ordinary  method  of  driving  work  between  the  lathe- 
centers?     How  should  threaded  work  be  driven?     What  is  a  bolt-dog? 

176.  Describe    one    or   more   methods   of  driving  work   between   centers 
which  allow  the  work  to  be  machined  its  full  length  without  being  reversed? 

177.  Describe  three  chucks  ordinarily  used  for  lathe  work. 

178.  Describe  one  or  more  special  chucks.     How  could  a  chuck  be  made 
without  jaws  for  holding  packing-rings?     What  is  a  wood-chuck? 


52S  MACHINE-SHOP  TOOLS  AND  METHODS 

179.  What  precautions  are  necessary  when  gripping  frail  work  in  the  ordi- 
nary chuck? 

180.  What  methods  may  be  used  for  testing  the  concentricity  of  chuck 
work? 

CHAPTER  XVI 

181.  What  is  a  lathe  arbor  or  mandrel  and  how  is  it  used? 

182.  Describe  the  plain  arbor,  giving  its  taper  per  foot. 

183.  What  is  the  construction  of  the  self-tightening  arbor?    What  objec- 
tion is  urged  against  it? 

184.  Describe  the  expansion  arbor.     How  is  it  used? 

185.  Describe  an  arbor  used  for  different  sizes  of  tapering  holes. 

186.  Describe  three  kinds  of  nut  arbors  and  tell  which  is  best  and  why. 

187.  What  special  arbor  method  is  sometimes  used  in  machining  armed 
pulleys? 

188.  How  may  arbors  be  forced  into  work  without  injuring  the  arbor? 

189.  Describe  one  design  of  arbor-press. 

CHAPTER  XVII 

190.  Describe  the  various  steps  necessary  in  machining  a   collar,  as  ex- 
plained on  pages  254  to  257. 

191.  Describe  the  operations  necessary  for  machining  the  shaft,  pages  257 
to  258. 

192.  How  should  a  side-tool  be  ground  and  set  to  give  the  best  finish  on 
the  end  of  a  shaft? 

193.  What  are  some  of  the  causes  of  chattering  mentioned  in  this  chapter, 
and  what  are  the  remedies? 

194.  Describe  the  operations  necessary  for  machining  a  bevel-gear  blank. 
How  may  the  beveled  face  be  turned  without  a  compound  rest? 

195.  What  precautions  are  necessary  to  avoid  mistakes  in,  adjusting  the 
compound  rest? 

196.  What  is  a  taper  attachment? 

197.  Describe  the  method  of  turning   tapers   (a)   by  taper   attachment, 
(6)  by  tail-stock  adjustment.     Give  an  approximate  rule  for  adjusting  the 
tail-stock  for  tapers. 

198.  Describe  the  steady  rest  and  cathead.     For  what  purposes  are  these 
devices  used? 

199.  In  what  cases  is  a  follower-rest  used? 

200.  Describe  a  special  method  of  machining  a  cone  pulley  with  several 
tools  cutting  simultaneously.     Explain  the  construction  of  the  chuck  shown 
in  Fig.  397. 

201.  Explain   the   operation  of   the   ball-turning  rest  illustrated  in  Figs. 
398  and  399.     Describe  other  methods  of  turning  balls. 

202.  Explain  the  general  principle  of  turning  curved  surfaces  with  guid- 
ing forms. 


QUESTIONS  ON  THE  TEXT  529 

CHAPTER  XVIII 

203.  Is  the  feed-belt  reliable  f®r  thread-cutting? 

204.  What  is  meant  by  the  term  lead  as  applied  to  screw-threads? 

205.  What  is  the  distinction  between  lead  and  pitch? 

206.  With   stud   and   spindle   1    to    1    and   6   threads   per   inch   on   the 
lead-screw,    compute   change-gears   for   6,    12,   and    13    threads    (all    single 
threads] . 

207.  What  is  a  translating-gear,  and  why  is  it  used? 

208.  .With  a  lead-screw  of  4-inch  turns,   compute   change-gears   (simple 
gearing)  for  cutting  a  thread  with  2  millimeters  lead. 

209.  Explain  a  method  of  cutting  fractional  threads  with  approximate 
change-gears. 

210.  Describe  a  method  of  setting  V  and  U.  S.  standard  thread-tools  for 
straight-screw  cutting. 

211.  Describe  the  same  for  cutting  tapered  screws. 

212.  What  is  a  thread  stop-gage,  and  how  is  it  used? 

213.  Explain  how  to  catch  the  thread  without  reversing  the  lathe. 

214.  How  may  multiple  threads  be  spaced  in  the  lathe? 


CHAPTER  XIX 

215.  What    is    the    difference    between    V    and    U.    S.    standard    screw- 
threads?     Which  is  the  stronger?     Which  is  the  more  durable? 

216.  Describe  the  Acme  thread. 

217.  In  starting  a  new  plant,  what  screw-threads  should  be  adopted  for 
general  purposes? 

218.  What  number  of   threads  per  inch  different  from  the  U.  S.  standard 
is  often  used  for  £"  screws? 

219.  What    is    meant    by    the    nominal    diameter    of    a    pipe?     By   the 
actual  diameter? 

220.  Where  is  the  extra  metal  added  to  "extra-strong"  and  "double- 
extra-strong"  pipe? 

221.  Describe  the  set  of  standard  machinists'  hand-taps. 

222.  Describe  the  pulley-tap. 

223.  What  taper  is  used  for  pipe-taps? 

224.  What  is  "hob"?    What  is  a  stay-bolt  tap? 

225.  Describe  the  process  of  making  a  solid  die. 

226.  Describe  one  form  of  adjustable  die. 

227.  What  method  is  suggested  for  retapping  old  dies? 

228.  Describe  the  "water-anneal"  process. 

229.  What  is  meant  by  backing  off  a  tap? 

230.  Describe  a  common  form  of   adjustable  tap-wrench. 

231.  Describe  a  simple  bolt-cutting  machine. 

232.  Describe  in  general  terms  the  die-head  of  a  bolt-cutting  machine. 


530  MACHINE-SHOP  TOOLS  AND  METHODS 

CHAPTER  XX 

233.  Name  and  describe  three  types  of  boring-bar. 

234.  What  methods  are  used  in  securing  the  cutters  in  a  boring-bar? 

235.  What  is  the  advantage  of  double  cutters? 

236.  Explain    the    action    of   the    star-feed    as    applied    to    sliding-head 
boring-bars. 

237.  How  may  the  star-feed  be  applied  to  lateral  feeding? 

238.  State  and  explain  three  methods  of  boring  tapered  holes  with  the 
boring-bar. 

239.  How  may  an  engine-cylinder  be  rebored  without  removing  it'  from  the 
engine-bed? 

240.  What  conditions  may  cause  chattering  in  the  use  of  the  boring-bar, 
and  how  is  chattering  remedied? 

241.  Describe  a  satisfactory  cutter  for  roughing  cuts,  for  finishing  cuts. 

CHAPTER  XXI 

242.  For    what    purposes    are    horizontal    boring-   and   drilling-machines 
used? 

243.  Describe    a    facing    attachment    used    on    the     horizontal    boring* 
machine. 

244.  How  may  a  horizontal  boring-machine  be  adapted  for  milling? 

245.  What  distinguishes  a  base-boring  machine  from  the  ordinary  boring- 
machine? 

246.  For  what  class  of  work  are  portable  boring-machines  used? 

247.  What  is  a  crank-boring  machine? 

CHAPTER  XXII 

248.  What  are   the   characteristic    features   of   the   vertical   boring-  and 
turning-mill?     What  are  its  advantages  for  turning  large  fly-wheels? 

249.  Describe  a  special  boring-machine  for  car-wheels.  . 

250.  Can  the  turret-head  be  advantageously  applied  to  vertical  boring-  and 
turning-mills? 

251.  What   can  you  say  about  the   adaptation  of  vertical  boring-  and 
turning-mills  to  thread-cutting  operations? 

CHAPTER  XXIII 

252.  Give  a  general  description  of  the  metal  planer. 

253.  What  is  the   construction  of  the  friction  feed-disk  commonly  used 
on  the  planer? 

254.  How   is   the   cross-head   automatically  fed? 

255.  Describe  the  system  of  gearing  that  drives  the  planer-table. 

256.  How  is  the  table  reversed? 

257.  Are  planers  always  equipped  with  a  positive  drive?    What  advantage 
is  claimed  for  the  "second-belt"  drive  referred  to  in  this  chapter? 


QUESTIONS  ON  THE  TEXT  531 


258.  What  conditions  as  to  strength  must  exist  in  a  satisfactory  open-side 
planer?     Describe  a  device  sometimes  used  on  the  ordinary  planer  for  planing 
wide  work. 

259.  Describe    the    mechanism    driving    the    ram    in   a   common    crank- 
shaper. 

260.  How  is  the  length  of  stroke  regulated  in  the  crank-shaper? 

261.  Describe  one  method  of  effecting  quick  return  in  the  planer. 

262.  What    is    the  difference    between    a    geared   shaper   and   a    crank- 
shaper? 

263.  What  is  a  traverse  shaper? 

264.  What  is  the  object  of  swiveling  the  tool-apron  of  the  planer? 

265.  Describe  a  simple  tool-lifter  for  under-cut  planing. 

266.  What    precaution    should    be    observed    in    adjusting    the    planer 
cross-rail? 

267.  How  may  work  be  held  on  the  planer-table  without  a  vise?     (Give 
two  methods). 

268.  What  is  an  angle-plate? 

269.  What  are  V  blocks?    What  are  straps? 

270.  What  precaution  is  necessary  in  blocking  up  work  on  the  planer-table? 
What  is  the  result  of  neglecting  this  precaution? 

271.  What  are  planer-centers  and  how  are  they  used? 

272.  Describe  a  concave  attachment  for  the  shaper,  a  convex  attachment. 

273.  Explain  the  "former  principle"  as  used  on  the  planer  for  planing 
curved  work. 

274.  Describe  a  method  of  cutting  rack-teeth  on  the  planer. 

275.  Describe  a  grinding  attachemnt  as  used  on  the  planer  and  shaper. 

276.  How  may  the  alinement  of  a  planer-bed  be  tested? 

CHAPTER  XXIV 

277.  How  does  the  slotting-machine  differ  from  the  shaper? 

278.  To  what  line  of  work  is  the  slotter  especially  adapted? 

279.  Describe  a  common  slotting-machine  tool. 

280.  Describe  a  rotating  tool-holder  for  use  on  the  slotting-machine. 

CHAPTER  XXV 

281.  What  is  a  key?  a  key-seat? 505 

282.  Describe  a  simple  key-seating  machine.     What  advantage  has  this 
machine  as  compared  with  the  slotting-machine? 

283.  Describe  a  key-seating  attachment  for  the  drill-press. 

CHAPTER  XXVI 

284.  What   are   the   essential   features  of   a   milling-machine? 

285.  Outline  the  feed-gearing  of  a  Universal  milling-machine. 

286.  What  is  a  plain  milling-machine? 


532  MACHINE-SHOP  TOOLS  AND  METHODS 

287.  What  advantage  has  the  planer  type  milling-machine? 

288.  Describe  the  vertical  milling-machine. 

289.  How  does  the  milling-machine  compare  with  the  planer  as  to  range 
of  work  and  economy? 

290.  What  is  slab-milling? 

291.  Name  and  describe  some  common  forms  of  milling-cutters. 

292.  What  is  meant  by  gang-milling? 

293.  What  two  processes  are  necessary  in  milling  a  large  dove-tail  slot 
from  the  solid? 

294.  Give   a   method   for   holding   two   shafts   parallel,   for   milling   key- 
ways. 

295.  Name  and  describe  a  cheap  form  of  cutter  used  in  emergencies. 

296.  Describe  a  rack  milling  attachment  for  the  milling-machine,  a  slot- 
ting attachment.     Name  some  other  attachments. 

297.  What  is  the  dividing-head  and  for  what  is  it  used? 

298.  What  is  the  difference  between  simple  and  compound  indexing? 

299.  What  is  differential  indexing? 

300.  With    change-gears    of    32,    40,    64,    and    72    teeth    determine    the 
arrangement  necessary  for  a  spiral  of  36"  lead  with  pitch  of  screw=£"  and 
worm-wheel  with  40  teeth. 

301.  Describe  a  taper  attachment  for  use  on  the  milling-machine. 

302.  How  may  abrupt  angles  be  milled? 

303.  What  is  the  circular  pitch  of  a  gear?  the  diametral  pitch? 

304.  What  method  may  be  used  to  mill  gears  too  large  to  be  held  on  a 
horizontal  arbor? 

305.  What  is  a  worm?    a  worm-wheel?    What  tools  are  used  in  cutting 
worm-wheels? 

306.  State  in  their  order  the  processes  for  cutting  a  bevel-gear. 

307.  Why   is   the    common   method   of   cutting   bevel-gears   theoretically 
incorrect? 

308.  What  considerations  govern  the  cutting  speed  of  milling-cutters? 

CHAPTER  XXVII 

309.  What  is  the  advantage  of  automatic  gear-cutting  machines? 

310.  What  is  the  principle  of  the  gear-shaper? 

311.  How  are  gear-shaper  cutters  ground? 

312.  What  is  the  principle  involved  in  the  Gleason  gear-planer? 

CHAPTER  XXVIII 

313.  How  is  emery  graded  as  to  coarseness? 

314.  What  three  materials  are  used  extensively  for  the  manufacture  of 
grinding-wheels? 

315.  For  what  class  of  work  is  the  universal  grinding-machine  used? 

316.  How  are  errors  due  to  eccentricity  of  the  head   center   avoided   in 
the  Universal  grinder? 


QUESTIONS  ON  THE  TEXT  533 

317.  What   is  the  effect   of  wearing  of  the  emery-wheel  in  grinding  a 
parallel  shaft?    How  may  this  effect  be  obviated? 

318.  How  is  the  back-rest  applied  to  the  universal  grinder? 

319.  What  provision  is  jnade  for^grinding  abrupt  tapers  in  the  universal 
grinder? 

320.  How  may  disk  work  be  ground  in  the  universal  grinder? 

321.  Describe  a  convenient  draw-in  chuck  for  disk-grinding. 

322.  What  is  a  surface-grinding  machine? 

323.  What   precaution    is    necessary  in    clamping   work   to   the    surface- 
grinder  table? 

324.  What  two  forms  of  emery-wheel  truer  are  used? 

325.  How  may  a  grinding  attachment  be  applied  to  the  lathe? 

326.  What  speed  is  permissible  for  emery-wheels? 

327.  What  considerations  govern  the  width  of  face  of  the  emery-wheel  for 
the  universal  grinder? 

328.  What  considerations  govern  the  traverse  per  revolution  of  the  work 
in  the  universal  grinder?     Give  opinions  of  experts  on  this  subject. 

329.  What  is  glazing  of  emery-wheels?     How  may  it  be  prevented? 

330.  What  causes  may  produce  chattering  in  cylindrical  grinding? 

331.  What  precautions  are  necessary  in  mounting  an  emery-wheel? 

332.  For  what  purpose  is  water  used  in   cylindrical  grinding? 

CHAPTER  XXIX 

333.  Name  several  kinds  of  wheels  used  in  the   polishing-  and  buffing- 
lathe. 

334.  How  is  emery  applied  to  polishing- wheels? 

335.  Name  several  polishing  materials  and  give  the  uses  of  each. 

336.  How  may  rag-wheels  be  cleaned? 

CHAPTER  XXX 

337.  What  is  a  jig?    What  are  the  advantages  of  the  jig? 

338.  What  provision  is  made  for  keeping  the  guiding  holes  in  jigs  from 
wearing? 

339.  How  may  the   cutting   edges  of   drills  and  reamers  be   kept   from 
touching  the  bushings  in  jigs? 

340.  For    what    purposes    are    jigs    generally    used    in    the    planer    and 
miller? 

341.  What  is  meant  by  machine  nomenclature? 

342.  Describe  a  convenient  system  of  machine  nomenclature. 

CHAPTER  XXXI 

343.  What  is  meant  by  lapping?    Describe  one  form  of  adjustable  lap 

344.  What  is  a  shrink-fit?     Give  a  formula. 


534  MACHINE-SHOP  TOOLS  AND  METHODS. 

345.  What   precaution  is  necessary  in  shrinking  on   collars    and    shaft- 
couplings? 

346.  Where    are    force-fits    used?    About    what    allowance    is    made    for 
force-fits? 

347.  Why  is  it  necessary  to  balance  pulleys  and  emery-wheels?    How  are 
they  balanced? 


INDEX 


,  PAGE 

Abrasive  materials,  measuring  and  designating 467 

wheels,  grading  of 467 

Adjusting  work  in  the  drilling-machine 110-111 

Angle  of  lathe-centers 224-225 

Angle-plates,  use  of,  on  planer 374 

drilling-machine 106 

horizontal  boring-machines 330,  331,  336 

vertical  boring  and  turning  mill 352 

Angles,  milling  of  abrupt 438-439 

Annealing  brass  and  copper 520 

cast  iron 519 

steel 304 

Arbor,  self-tightening 247 

Arbors,  centers  in 251,  253 

,  classification  of 246 

,  expansion 248 

for  large  work 250,  253 

for  tapering  work. 248 

,  instructions  for  use  of,  on  the  miller 454 

,  methods  of  forcing  into  work 250-253 

,  nut 248-250 

,  plain 246-247 

Attachment,  boring-tool,  for  lathes 213 

,  concave,  for  shapers 378-379 

,  convex,  for  shapers 379-380 

,  Fifield  drilling 75-77 

,  grinding,  for  planers 384 

shapers 385,  386 

,  high-speed,  for  drilling-machines 103-104 

,  key-seating,  for  drilling-machines 396 

,  rack-cutting,  for  miller 422-423 

,  rotary,  for  miller 419-424 

,  slotting,  for  miller 423 

,  taper,  for  lathes 170-264 

miller 438 

,  vertical  milling 422 

,  wide-angle  spiral,  for  miller 421 

535 


INDEX 

PAGE 

Attachments,  ball-turning,  for  lathes 274 

,  boring-machine  facing , 331-332 

,  grinding,  for  lathes 384,  489 

Back  gearing 80-83,  92, 159-161,  400 

Back  rests,  use  of,  in  cylindrical  grinding 477,  480 

Balancing  cutter-heads 512 

emery-wheels 512 

pulleys 511-512 

Ball-turning 273-276 

Base-boring  and  drilling  machines 334 

Bath  indicator 245,  268 

Bell  center-punch 229-230 

Bevel-gear  planer,  Bilgram's 466 

,  Gleason's 461-466 

Bevel-gears,  length  of  face 441,  451 

,  milling  teeth  of 447-451 

,  selecting  cutters  for 440,  441,  450-451 

,  turning 259-261 

Bevel  protractor,  universal 26-28 

Bilgram  bevel-gear  planer 466 

Bits,  wood,  and  holder 137-139 

Blocking  up  centers  on  miller 444 

Bolt-cutter 309-312 

-dog 235 

Bolts  and  nuts,  milling  of 436 

Boring  a  steam-engine  cylinder 315-317 

Boring-,  drilling-,  and  milling-machines,  portable 340 

Boring-  and  turning-mills,  vertical,  advantage  of,  in  large  work 342 

,  cutting  threads  on 355 

,  examples  of  work  on 342-344,  349-353 

,  turret-heads  for 354-355 

Boring-bar  cutters 314,  317,  320,  326 

,  causes  of  chattering  of 326 

,  shapes  of 326-327 

,  feeding  by  the  lathe-gearing 321-322 

laterally  with  star  feed-device 322-323 

longitudinally  with  star  feed-device 319-320 

,  fixed  head 317-319 

,  methods  of  driving    320-321 

,  sliding  head 319-320 

Boring-bars 314-327 

Boring-machine,  crank 341 

,  facing  attachment  for 331-332 

,  horizontal,  description  of  typical 328 

,  milling  work  on 333-334 

,  rotary  tables  for 333 

,  work  of 331-334 

,  special 340 

Boring-machines,  securing  cylinders  on 315-317,  338-340 


INDEX  537 

PAGE 

Boring-machines,  universal 340 

Boring-mill  tools r  ; 351-352,  355 

Boring  taper  holes  with  boring-bar.  4^.. 324-325 

Boring-tool  attachment  for  lathes.  .  . .  fl 213 

,  feeding  back  and  forth 255 

Box  tools 200-201 

Brush-wheels 494 

Buffing  and  polishing 492-495 

Caliper,  hermaphrodite 6,  230 

,  large  micrometer 10-11 

,  screw-thread  micrometer 13 

Caliper-gages 15-16 

Calipers,  double 5 

,  friction-joint 5 

,  micrometer 9 

,  setting 8,  238 

,  spring-joint 4 

,  thread 6-8 

,  vernier 8-9 

,  graduations  on  micrometer '. 10 

Car- wheels,  special  boring-mill  for 353 

Case-hardening,  receipts  for 520 

Cast  iron,  to  harden 519 

Cat-head 267-268 

Center-drills  and  reamers 230-232 

Center-gage 18,  283-285 

Centering-machine 230-231 

Centering-tool,  lathe 259 

Centering  work  with  special  accuracy 231 

Center-punch 41 

,  Bell ,  .  . 229-230 

,  turning  and  knurling  of..  .  .... 261 

Center-square 229 

Centers,  angle  of ........ 224-225 

,  blocking-up,  on  miller ............. 444 

,  female ,..".. ......... 228 

,  methods  of  making,  in  work 228-232 

,  method  of  grinding 225-226 

,pipe 228 

,  precautions  as  to 225-227 

,  proportions  of,  in  work 228-229 

,  square 227 

,  taper  and  angle  of 224-225 

Change-gears,  approximate,  for  fractional  threads 283 

for  thread-cutting,  computing 279-283 

Chasers,  die 311-313 

Chattering  (foot-note) 255-256 

in  cylindrical  grinding ...   491 

planer  work 376 


538  INDEX 

PAGE 

Chattering  with  boring-bar 214,  326-327 

Chipping,  precautions  to  avoid  breaking  edge  of  work 42-43 

,  smooth 42 

Chisel,  cape 38,  40 

,  difficulty  with,  when  corners  wear  tapering 38 

,  cow-mouth 41 

,  diamond-point 40 

,  flat 37 

,  oil-groove 40-41 

,  side 40-41 

Chisels,  grinding  of 37-38,  43 

,  when  to  use • 43 

Chuck,  machining  back  plate  of 238 

,  use  of,  on  miller 439 

,  universal 239 

Chuck-jaws  for  face-plate 242 

Chucks,  combination 240-241 

,  draw-in 180,  439,  482-483 

,  drill 128 

,  home-made 243 

,  independent 237-238 

,  magnetic 485 

,  valve 242 

with  slip  jaws.  . . 241 

,  wood 244 

Chuck-work,  testing  concentricity  of 244-245 

Compound  indexing  on  miller 430-431 

Compound  rest  of  lathe,  precautions  as  to  angle  of 260-261 

Concave  attachment  for  shaper 378-379 

Cone-of-gears  feed 83,  92, 157,  350,  401 

Cone-pulley,  special  method  of  machining 272-273 

Connecting-rod  strap,  peening  a 34-35 

Convex  attachment  for  shaper 379 

Crank,  machining  a  small 269-270 

Cross-rail  adjustment,  planer. 372 

Cutter,  bolt 309 

Cutter-head,  balancing  of 512 

Cutter-heads 314,  317,  318,  319,  322 

Cutters,  boring-bar 314,  317,  320,  326 

,  direction  of  rotation  of  milling 451 

,  epicycloidal  system  of  gear-tooth 440 

,  feed  of  work  to,  in  milling 453 

for  shaping  large  curves,  cheap  method  of  making 218 

,  involute  system  of  gear-tooth 439 

,  milling,  various  shapes  and  names  of 407-410 

,  selecting  gear  tooth 439,  440-441,  450-451 

,  single  and  double,  compared 317 

Depth-gage,  micrometer 13,  J  5 

Diameters  of  stock  for  hexagon-  and  square-head  bolts 520 


INDEX  539 

PAGE 

Diametral  pitch 440 

Diamond  emery-truer .*, 488 

Die,  geometric  screw-cutting i 205 

Die,  making  a  solid.  ......" 300-302 

Die-head  for  bolt-cutting  machine 312-313 

Dies,  adjustable 302 

,  clearance-holes  of 301 

,  chamfering 301,  313 

,  heel-clearance  of 300,  302 

,  lands  of 300 

,  retapping  old 302 

,  solid 298,  300,  302 

,  spring 205 

,  square 298,  300 

,  tempering 307 

,  thread 298-303 

Differential  indexing 431-434 

Direction  of  rotation  of  milling  cutters 451 

Disk -grinding 481 

Dividers,  universal 5-6 

Dividing  head 424-430 

Dog,  bolt 235 

,  driving  work  by  a  common  lathe 233 

on  centers  without  a 236 

for  taper  work 234 

threaded  work 234 

taper  milling 437-438 

,  using  a  double-end 233 

Dovetail  slot,  milling  a 415 

Double  caliper 5 

Drift,  .definition  of  a 42 

,  key 42 

,pin 42 

Drill  (machine),  adjusting  work  on,  by  use  of  tram 110-111 

,  back-geared 79- 

,  automatic  stop 84 

,  feed-gearing 83-84 

,  hand-feed 84 

,  head 84 

,  quick-return 84 

,  table  adjustment 84-86 

,  back  gear  of 80-83 

,  breast 75-76 

,  character  of  work  on 104 

,  holding  work  on 105-108 

,  round  work  on 107 

,  horizontal  drilling  and  boring 328-341 

,  portable 77-78 

,  protecting  finished  work  on 106 

,  radial,  arrangement  of  driving-shafts 87,  91-92 


540  INDEX 

PAGE 

Drill  (machine),  depth  gage  for 90-91 

,  radial,  feed  gearing 89,  92 

,  general  description 86 

,  hand-feed  and  quick  return 89-90 

,  reversing  mechanism 87-89 

,  tilting-table  for 95-96 

,  universal 94-95 

,  ratchet 74-75 

,  starting  a  hole 104-105 

,  turning  hubs  on 108-1 10 

,  use  of  angle-plates  on 106 

,  upright,  with  revolving  table 96,  98 

,  vises  for 106,  107,  108 

Drill  and  reamer  sockets,  special,  for  jigwork .   499 

Drill,  broken-tang  split  sleeve  for 130-131 

,  a  cheap  device  for  driving 127 

Drill-chucks 128,  129 

Drill-grinder  and  -surface-grinder  combined 486 

Drill-holder,  the  lathe-dog  as  a 130 

Drilling,  a  hazardous  practice  in 131 

Drilling  attachment,  Fifield 75-77 

,  high-speed 103-104 

,  deep 121-122 

Drilling  hard  metal 124 

oil-holes  in  pulley-hubs 108, 109 

Drilling,  lubricants  used  for 123 

Drills,  bottoming 120 

,  effect  of  errors  in  grinding 116 

,  definition  and  classification  of 112 

,  feeds  of 93-94,  124 

,  flat 118-119 

,  gage  for  twist '20,  23 

grinding 114-116 

,  grinding-machines  for 470,  486 

,  high-speed  steel  for 123-124 

,  oil-tube 121-122 

,  pin,  or  counterbores 119-120 

,  slotting 120-121 

,  speed  of 123 

,  straight-shank  twist 117 

,  straight- way  or  farmer 117-118 

,  three-groove  and  four-groove  twist 117 

,  tit 120 

•  ,  twist 112-117,  121-122 

,  clearances  of 113 

,  nomenclature 112-113 

Drills  (machines),  multispindle 96,  99-101 

,  radial,  important  principle  in  design  of 93 

,  motor-driven 94 

,  sensitive 78-79 


INDEX  541 

PAGE 

Drills  (machines) ,  sensitive  friction 79-80 

,  suspension i 95 

,  turret ^ 99-103 

Drill-shanks,  table  of  Morse  taper 130 

Drill-sockets 125-127 

,  abuse  of 1 25 

or  holders,  lathe 128-129 

,  positive-grip 125 

Drive  fits 510 

Driving  work  on  centers  without  a  dog 236 

Eccentricity,  causes  of,  in  grinding 491 

lathe- work 227 

Effect  of  errors  in  grinding  drills 116 

Elevating  tool-rest  on  lathe 167 

Emergency  milling 417 

Emery,  measuring  and  designating 467 

Emery  grinder,  portable 489 

Emery-stick 495 

Emery-wheels,  balancing  of 512 

,  comparison  of  coarse  and  fine 490 

,  dressers  for 487-488 

,  glazing  of 490 

,  grading  of 467-468 

,  mounting  of 491,  512 

,  speed  of 489-490 

,  width  of  face  of,  for  cylindrical  grinding 490 

Engine-lathe,  turrets  for 198-199 

Engine-lathe  work 254-293 

Epiclycloidal  system  of  gear-tooth  cutters 440 

Etching  fluid,  relieving  taps  by 307 

Expansion-chuck 243 

Expansion-reamers 136 

Extension  head  for  planers 362 

External  and  internal  thread-gages 17-18 

Extra  heads  on  planers 363 

Feed,  automatic  chuck  and  roller  on  turret  lathe 190-191 

Feed-clutches  on  the  lathe 158-159 

Feed,  cone-of-gears,  mounted 83,  92, 156,  350,  401 

Feed-disk  for  planer 356 

Feed  for  miller 453 

Feed-gearing  in  cross-head  of  planer 356-359 

,  miller 401-402 

,  shaper 366 

Feed-mechanism  of  lathes 149, 156, 159,  161-162 

Feed  of  drills,  rate  of 93,  94, 124 

Feeds,  rate  of,  for  lathe-work - 173 

Fellow's  gear-shaper 458-461 

File-brush  and  file-card 51 


542  INDEX 

PAGE 

File  sections  and  corresponding  names 44-46 

File  should  not  be  lifted  on  return-strokes 59 

Filing  a  rectangular  recess 57 

broad  surfaces 55 

curved  surfaces 56-57 

Filing,  changing  direction  of  strokes  of 54 

,  moisture  causes  glazing 52 

Filing  lathe-work 57-58 

,  danger  of  clothing  being  caught 58 

,  dangerous  without  file-handle 67 

,  speed  of  the  work 58 

Files,  care,  of,  cases  in  which  new  files  should  not  be  used 59 

,  classification  with  respect  to  shape 48 

,  coarse  and  bastard,  used  on  heavy  and  coarse  work 52 

,  convexity  increases  the  "bite" 49 

compensates  for  rocking  motion. 49 

,  cross-filing  and  draw-filing 50-51 

,  curving  for  special  work 57 

,  dead-smooth  for  extra  fine  finish 52 

,  distinction  between  the  terms  double-cut  and  second-cut 48 

,  efficiency  of  hand-cut 49 

,  general  classification 44-45 

,  grades  and  names 47 

,  grasping 49-50 

,  increment-cut  versus  hand-cut 49 

most  used  in  machine-shop 52 

,  pinning,  prevention  of 51-52 

,  pitch  of  teeth  varies  with  length  of 46 

,  safe  edge 51 

,  stub  and  holder 57 

,  tang  and  heel,  meaning  of 44 

,  uses  of  hand,  pillar,  mill,  equalling,  and  round 52-5 

Finishing  a  flat  surface 54 

Flat  drills 118 

Floating-shank  reamer 355 

Force  fits 509-510 

Former,  use  of,  for  machining  curved  shapes 277,  379-382 

Forming  tools  in  screw-machines 205 

Friction-disk  mechanism  for  feeding  milling-machine  table 402 

Gage,  adjustable  limit 17 

,  caliper 15-16 

,  decimal 24-25 

,  jobber's  drill 23 

,  micrometer,  inside 13 

,  depth 13 

,  theory  of  the  Edison  wire 24 

,  thread  and  center 18,  283-285 

,  thread-pitch 18 

,  U.  S.  standard  thread 19 


INDEX  543 


5,  wire  and  twist-drill 20-24 

,  wood-  and  machine-screw.  .  .  ." 24 

Gages,  collar  and  plug I 16 

,  distinction  between.  Stubs'  wfre  and  Stubs'  steel  wire 23 

drill  and  Stubs'  steel  wire 23 

,  external  and  internal  thread 17 

,  limit.. 16-17 

,  to  prevent  wasting  time 28 

,  remedy  for  confusion  in  use  of  wire 24 

,  seasoning  steel  for  caliper  and  collar  and  plug 29 

,  surface 20 

,  table  of  wire 513 

twist-drill 514 

wood-  and  machine-screws 515 

Gang-cutters  for  gear-teeth 458 

Gang  milling 412 

Gap-lathe .' 172 

Gas-engine  frame,  milling  a 413-415 

Gear-cutter,  Gould  and  Eberhardt  automatic 455-457 

Gear-cutting  on  planer  and  shaper 382 

miller 439-444,  447-451 

,  care  as  to  lost  motion  of  screws 442,  450 

Geared-head  lathes 163-164 

,  Gleason 461-466 

Gear-shaper,  Fellow's 458-461 

Gears,  bevel,  cutters  for 440-441,  450-451 

,  change,  computing 279-283 

,  circular  pitch  of 440 

,  sliding-key 83-84,  92 

,  triple,  for  lathe 163 

Gear-tooth  cutters,  selecting 439,  440-441,  450-451 

Geometric  screw-cutting  die-head 205 

Glazing  of  emery-wheels 490 

Graver  made  of  square  file 67 

Grinder,  combined  drill  and  surface 486 

,  draw-in  chuck  for 482-483 

,  floor,  with  surface  attachment 486-487 

,  portable 489 

Grinders  for  lathe-  and  planer-tools 468-470 

Grinding  attachments  for  lathes 384,  489 

planer  and  shaper 384-385 

ends  of  collars  and  bushings 481 

parallel  shafts 477-479 

tapers 480-481 

work,  economy  of 476 

,  roughing  and  finishing  cuts — lathe  dispensed  with 476,  484 

Grinding-machine  for  reamers,  milling  cutters,  etc 470-471 

Grinding-machine,  plain 471.  473 

,  surface 484-185 

,  universal 471-475 


544  INDEX 

PAGE 

Grinding,  causes  of  chattering  in 491 

,  disk 481-482 

,  internal 483-484 

,  use  of  water  in  cylindrical 491 

.valves  and  joints 507 

,  work-speed  and  rate  of  wheel- traverse 490 

Hack-saw , 73 

Hammer,  peen  of 31 

,  striking  two  blows  for  one  with  the 32 

,  proper  method  of  using  the 31 

Hammers,  common  forms  of 30 

,  fitting  the  handles  of 31 

,  material  of 30 

,  soft 35 

,  weight  of 30 

Hand-lathes • 146 

Hardening  cast  iron 519 

reamers 144 

Hard  metal,  drilling 124 

Hermaphrodite  caliper 6,  230 

Hexagon-head  bolts,  diameter  of  stock  for 520 

High-speed  attachment  for  drilling-machines 103-104 

steel 123,  173,  453 

Hobs,  hobbing  worm-wheels 445-447 

Holding  work  on  planer  by  pins  and  stops 373-374 

Hollow  spindle,  advantage  of,  in  lathes 175 

Horizontal  boring-  and  drilling-machines 328-340 

Ideal  condition  of  lathe-centers 224 

Inch-turns,  meaning  of 279 

Indicator,  bath 245,  268 

Index  centers,  plain 444 

Indexing,  compound 430-431 

,  differential 431-434 

mechanism  of  Gould  &  Eberhardt  gear-cutter 457 

,  simple 430 

Interchangeable  system  of  manufacturing 496 

Internal  grinding 483-484 

Involute  system  of  cutters 439 

Jig  for  drilling  ball-handles 501 

drilling  tail-stock  clamp-levers 501 

cylinder-heads 496-497 

steam-chest  cover 497 

Jig-making,  an  excellent  example  of 497-501 

,  leaving  space  between  bushing  and  work 504 

Jigs  496-504 

as  used  on  planer  and  miller 502-503 

,  importance  of,  for  interchangeable  work 496 

,  special  drill  and  reamer  sockets  for 499-500 


INDEX 


545 


PAGE 

Key-drift , 42 

Key -seating  attachment  for  upright*  drill i 396 

machines ^ 395-396 

Key-seat  rule r T .  v  . .  .  .> 24-25 

Key-seats  and  key-fitting 394-395 

Keyways,  milling 416-417 

Knurling-tools 262-263 

Lands  of  dies . 300 

Lapping  centers 135,  136,  253 

Laps  and  lapping 506-507 

Lathe,  advantage  of  offset  tail-stock 176 

,  advantages  of  hollow  spindle 175 

,  compound  rest  of 148,  165-166,  260-262,  286 

,  cutting  speeds  of  the 172-173 

,  engine,  general  description  with  names  of  details 147-149 

,  feeds  of  the 173 

for  turning  locomotive  driving-wheels 172 

,gap 172 

,  increasing  the  swing  of,  meaning  of  word  '  swing ' 172,  173-175 

,  instrument  for  measuring  cutting  speed  of  the 173 

,  pit 171 

,  primitive  form  of  the 145-146 

,  pulley 170-171 

,  purchasing  a 175 

,  reverse  gears  under  head  stock 151 

,  screw-cutting  mechanism  of 149 

,  special,  for  high-speed  steel 164-165 

,  testing  alinement  of  a 176-177 

,  tool-room 172 

,  triple  gear 163 

,  use  of  screw  as  feed-rod 149 

Lathe-  and  work-centers 224-232 

Lathe-bed  easily  twisted 176 

Lathe-centers,  grinder  for 226 

,  importance  of  keeping  them  true 225-227 

,  shaping  the  point  to  lessen  grinding 226 

,  taper  of,  angle  of  point 224-225 

Lathe  change-gears,  mounted 156-158 

Lathe  mandrels  or  arbors 246-253 

Lathe  slide-rest 146 

Lathes,  analysis  of  back  gear  of 159-161 

,  bevel-gear  reverse  in  apron  of 158-159 

,  classification  of 145 

,  elevating  tool-rest  for 167 

,  feed-clutches  of 158 

,  feed-mechanism  of 149 

,  geared  head 163-164 

,  hand 146-147 

,  open-side  tool-rest  for 167 


546  INDEX 

PAGE 

Lathes,  plain  rest  for 165 

,  raise-and-fall  rest  for 165 

,  spur-gear  reversing  mechanism  of 161-162 

,  taper  attachment  for.  .  .  K. 170 

,  three-tool  shafting-rest  for 168 

,  turret,  see  Turret  machines. 

Lathe-tools  (see  also  Tools) 208-223 

Lathe-work,  driving  of 233-245 

,  engine 254-293 

Lead  of  threads,  meaning 278 

Lubricants  for  turning  and  drilling 223 

Machine  nomenclature 504-505 

Machine,  nut-tapping 313 

Machines,  drilling 74-111 

,  key-seating 394-396 

Machining  a  collar 254 

flanged  cylinder 338 

small  crank 269 

Magnetic  chucks 485 

Mandrels,  lathe  (see  also  Arbors) 246-253 

Measuring-machine,  Sweet's 11 

,  the  Pratt  and  Whitney 13 

Metre,  the  national  prototype 2 

,  value  in  English  measure 2,  282 

Metric  and  fractional  threads,  computing  change  gears  for 282 

Metric  system,  when  legalized  by  Congress 2 

Micrometer  calipers 9-13 

,  large 10-11 

depth  gage 13 

disks  and  measurements 383,  437 

gage,  inside 13 

screw-thread  caliper 13 

Mill,  hollow 202 

,  straddle 436-437 

Miller  arbors,  instruction  for  use  of 454 

attachments,  see  Attachments. 

centers,  blocking  up  for  large  work 443-444 

Miller,  boring  on 417 

,  dividing  head 424,  428-430 

,  feed-gearing.  , ..... 401-402 

,  holding  work  on,  without  special  fixtures 417-418 

,  open  side 404 

,  planer-type ......... 404,  405 

,  plain 402-404 

,  use  of  chucks  on  the ....  .0 ........ 439 

,  vertical,  work  on. .„.,.... 413-419 

,  vertical.  .  * . ... 405-407 

Milling-cutters,  computing  change-gears  for  cutting  spirals 434-436 

,  direction  of  rotation 451-453 


INDEX  547 

PAGE 

Milling-cutters,  feed  of  work  to 453 

,  form 4. .'" 407,  410 

Milling  abrupt  angles & 438-439 

bolts  and  nuts.  . .  7. 436-437 

dove  tail  slot 415-416 

gas-engine  frame 413-415 

gear-teeth,  bevel-gears 447-450 

,  common  method  theoretically  incorrect  for  bevel-gears  450-451 
,  precautions  as  to  lost  motion  or  back-lash  of  feed-screws  442,  450 

,  special  method  for  large  gears 443-444 

,  spur-gears 441-443 

,  worm-gears 445-447 

keyways 416-417 

parallel  pieces  of  different  widths  with  same  cutters •"-***•  •  •  •  •   420 

rack-teeth 451 

Milling,  emergency 417 

,  gang 412,  458 

,  slab 407-411 

,  slot 412-413 

steel  castings 415 

,  taper,  special  dog  for 437-438 

Milling-machine  driving-gear 398-400 

vises 420-421 

Milling-machines  and  planers  compared 407 

Milling-machines,  work,  etc 397-454 

Morse  tapers. 130,  224,  349 

National  prototype  metre.    > 2 

Nomenclature,  system  of  machine 504 

,  twist  drill 112 

Nut-tapping  machine ; 313 

Oil-tube  drills 121 

Open-side  miller 404 

planer 362 

Ornamental  finish  with  emery  and  stick 65 

Paper  weight,  turning  a 271-272 

Parallel  blocks,  adjustable 375-376 

Peen,  meaning  of 31 

Peening  a  connecting-rod  strap 34-35 

Peening,  enlarging  piston-ring  by 35 

.  straightening  shafts  by 33-34 

Pin-drift 42 

Pins  for  holding  shaper  and  planer  work 373-374 

Pipe,  nominal  and  actual  diameter  of 296 

Pipe-threads,  tap-drill  sizes  for. 516 

Piston-ring  chuck 243 

Pitch  of  gear-teeth 440 

thread,  meaning  of 278 


548  INDEX 

PAGE 

Pit-lathes. 171 

Planer  and  shaper,  difference  between 364 

Planer-bed,  testing  of 387 

Planer-table,  care  of 385 

,  movement  of 359-361 

tools 211,  214,  215,  217-219,  376-377 

,  backward  offset  of,  to  prevent  chattering 217-219,  376 

work 372-384 

Planer,  blocking  up  work  on  the 375 

,  feed-disk  of ' 356-358 

,  feed-gearing  in  cross-head  of 356-359 

,  gear-cutting  on 382 

,  general  description 356 

,  open-side 362 

,  second  belt-drive  for 361-362 

,  swiveling  the  tool-slide  and  tool-apron  of 370-371 

Planers,  adjusting  the  cross-rail 372 

,  extension-head  for 362-363 

,  extra  heads  for. 363-364 

,  ratio  of  table  reverse 361,  362 

,  tool-lifter  for '. 371 

,  vises  for 372-373 

Planing  curved  work 377-388 

irregular  forms 379-382 

,  shape  of  work  not  a  duplicate  of  former 380-382 

rack  teeth 382-383 

Planing,  precaution  as  to  pressure  of  straps 375 

Pliers 73 

Polishing-  and  buffing-lathe 492 

Polishing  brass,  steel,  nickel,  etc 493-495 

Polishing-clamps 58-59 

Polishing  in  the  lathe 58 

Polishing  materials,  crocus,  rouge,  pumice,  emery,  etc 494-495 

Polishing,  ornamental,  with  emery  and  stick 65 

Polishing-wheels,  brush,  wooden,  walrus,  rag,  grease,  etc 493-495 

,  speed  of 495 

Presses,  arbor 253 

Protecting  finished  work  from  set-screw  of  lathe-dog 234 

on  drilling-machine 106 

thread  in  screw-cutting 234-235 

Protractor,  universal  bevel 26 

Pulleys,  balancing  of 511-512 

Questions  on  the  text 521-534 

Quick  return  of  drill-spindle 84,  89 

planer-table 361,  362 

shaper-ram 367 

Rack-teeth,  planing 382-383 

Rake  of  brass  tools 222 

lathe  tools.  .  .219 


INDEX  549 

PAGE 

Reamers 132-144 

and  drills  compared i 132 

,  adjustable »•> 136 

,  allowance  for  wear  and  stoning 143 

,  blanks,  turning  off  decarbonized  surface 144 

,  body  clearance  of 142 

not  milled  to  extreme  edge 142 

,  causes  of  chattering  of 142 

,  chucking 132, 137 

,  considerations  governing  number  of  cutting-edges 140 

,  definition  and  classification  of 132 

,  eccentric  relief  and  flat  relief 142 

,  expansion 138 

,  floating  shank 355 

,  hand 132-133, 136,  139-140 

,  hardening  of 144 

,  lapping  centers  of 135 

,  miscellaneous 143 

,  object  of  unequally  spacing  teeth 143 

,  resetting  rose  and  fluted 135 

,  rose  and  fluted,  compared 134 

,  roughing  taper 140 

,  shapes  of  cutting  edges  of 140 

,  shell  and  arbors  for 134-135 

,  solid  fluted 133 

,  special  sockets  for 499 

,  spiral 133 

,  standard,  allowance  for  cutting 133,  134 

,  tables  of  cutters  for 141 

,  taper  of  rose  and  fluted 133-134 

,  tapering 139 

,  to  sharpen 520 

Receipts  for  hardening,  case-hardening,  annealing,  etc 519-520 

Renold  silent  chain 343 

Rest,  compound 148,  165,  166,  260-262,  286 

,  elevating-tool 167 

,  follower 268-269 

,  open-side  tool 167 

,  plain 165 

,  raise-and-fall , 165 

,  slide 146 

,  steady 231,  267 

,  three-tool  shafting 168 

Riveting,  special  method  for  large  pins 32-33 

Rotating  tool-holder 393 

Rule,  hook 3 

,  key-seat 24-25 

Rules,  wood  and  steel 3 

Scraper,   double  end 61-62 


550  INDEX 


Scraper,  causes  of  chattering  in  using 63,  66 

,  cheap  steel  not  economical 61 

for  interior  curves 63-64 

,  grasping  the 62 

,  grinding  and  oil-stoning  the 61,  67 

,  hooked  form  of 62 

,  ornamental  work  with 63 

,  precautions  against  drawing  temper  in  grinding  the 62-63 

,  wasting  time  in  use  of  the 63 

,  special  form  of,  for  broad  surfaces 64 

,  typical 61 

Scrapers,  use  of,  in  lathe-work.  , 65-67 

dangerous  without  handles 67 

Screw-cutting,  see  Thread-cutting. 

Screws,  compensating  for  errors  in .' 12 

,  dog  for 234-235 

Screw-thread  micrometer  caliper 13 

Screw-threads,  taps,  dies,  etc 294-314 

Seasoning  steel  used  for  gages 29 

Setting  calipers 8,  238 

thread-tools  for  straight  and  taper  work 283-284 

Shaper 364-372 

,  concave  attachment  for 378 

,  convex  attachment  for 379 

,  crank 364-367 

,  cutting  gears  on 382 

,  driving-gear  of  crank 366 

,  feed-gearing  of 366 

,  Fellow's  gear 458-461 

,  geared 368 

,  quick  return  in  the  crank 367 

,  ram  movement  on  geared,  and  crank 368 

ram,  motion  of .  . 367 

,  stroke  adjustment  of  the 367 

,  surface-grinding  attachment  for 385-386 

,  swiveling  the  tool-slide  and  tool-apron  of  the 370-371 

,  traverse 368-369 

,  tool-lifter  for 371-372 

,  vises  for 372-373 

,  work  on 372 

work,  pins  for  holding 373-374 

,  variable-speed  gearing  for 368-370 

Shrink  fits,  allowance  for 508-510 

Single  and  double  threads 278-279 

Slab-milling 407-411 

Slide,  cross,  for  turret-lathe 146 

Slide-rest  of  lathe 146 

Sliding-key  gears 92 

Slot-milling 412-413 

Slott  ing-attachment  for  milling-machines 423 


INDEX  551 


PAGE 


Slotting-machine,  general  description. , 388- 

,  portable ^ 389-391 

,  ram  movement  of .  .  ^ 388 

,  rotary  tool-holder  for 393 

,  table  movement  of 388 

tools 391-393 

work 388-389 

Spacing  cutting-edges  of  reamers 143 

numbers  used  with  dividing  head 432 

of  multiple  threads 292 

Special-gear  machines '. 455-466 

Speed  for  cutting  in  the  lathe 172 

of  drills 123 

emery-wheels 489-490 

milling-cutters 453 

Spirals,  computing  change-gears  for  cutting 434 

,  miller  attachment  for  wide  angle 421 

Square,  combination 26 

,  machinists'  try 25 

Square-head  bolts,  diameter  of  stock  for 520 

Standard  set  of  lathe-tools 208 

Standards  of  length 1-2 

Star-feed  mechanism 319,  322 

Starting  the  hole  in  drilling 104 

Steady  rest 231,  267 

Steel,  annealing 304 

,  seasoning '. 29 

,  tempering 307 

Steam-engine  cylinders,  boring 315-317 

,  reboring  on  engine-bed 325 

Straddle  mill 436 

Straight-edge,  definition  of 60 

Straightening  a  cast-iron  bar 34 

by  dropping  process 34 

peening 33 

screw-press 33 

Stubs'  gages,  distinction  between  Stubs'  wire  and  Stubs'  steel-wire  gages 23 

Surface-gages 20 

Surface-plate,  design  and  care  of 60 

,  object  of,  description 60 

,  using  the 61 

Suspension  drilling-machines 95 

Swing,  meaning  of,  as  applied  to  lathes 173-175 

Table,  tilting,  for  radial  drill 95 

Table  of  constants  for  diameter  at  root  of  V  and  U.  S.  standard  threads 519 

machine-screw  gage  diameters 515 

Table  of  Morse  tapers 130 

tap-drill  diameters  for  machine-screws 517 

pipe 51S 


552  INDEX 

PAGE 

Table  of  tap-drill  diameters  for  U.  S.  standard  screws 518 

V  threads 516 

twist-drill  gage  diameters 514 

wire  gages 513 

Tail-stock,  adjusting  for  taper  work 263-264,  266 

Taper  attachments,  errors  in  graduation 265 

shaft,  fitting  to  collar 265 

turning  by  taper  attachment 263-265 

,  examples  of 258-263 

on  the  flat  turret-lathe 206-207 

Tapering  screws,  setting  thread-tool  for 284 

Tap,  making  a  taper 303-306 

lever  or  wrench 308 

Tapping  holes 308 

steel,  lard-oil  and  graphite  for 308 

Taps,  backing  off 306 

,  bottoming 298 

,  grooving 306 

,  machinist's  hand 297-298 

,  machine 298,  299 

,  pipe 298,  299 

,  plug 297 

,  pulley 298,  299 

,  relieving 307 

by  etching  fluid 307 

,  stay-bolt % 298,  300 

,  taper ' 297 

,  tempering 307 

,  threading 305,  306 

Templets 19 

Threading  large  work 308-309 

Threads,  acme 295 

,  pipe 296-297 

,  screw,  some  practical  considerations  concerning.  .       294-296 

,  single  and  double '.  .  .   278-279 

,  square 295 

,  U.  S.  standard  and  V 294-295 

,  variations  from  U.  S.  standard 296 

,  Whitworth 294 

Thread-cutting,  catching  the  threads 289 

,  computing  change-gears  for 279-283 

in  the  engine-lathe 278-293 

,  principles  of 278 

turret-machines.  .  . . , 204 

,  left-hand  worm 290 

,  precautions  in  connection  with 285-286 

,  spacing  multiple  thread^ 292-293 

,  square  threads 287-289 

,  stop-gage  for 286-287 

,  theoretical  difficulties 291 


INDEX  553 

PAGE 

Thread-cutting,  use  of  compound  rest  for 286 

Thread-calipers '. .  .  v 6 

Thread-gage fc . 18,  283 

Thread-pitch  gage -* ™ 18 

Thread-tool  and  holder v 215 

,  Rivett-Dock  holder 215-217 

Thread-tools,  setting 283-284,  285 

side  clearance  of,  for  square  thread 291-292 

Tool,  knurling 262,  263 

Tool-holder  plan 212-219 

Tool-lifter  for  planer 371 

Tools,  advantage  of  backward  offset  in  planer 217-219 

,  a  standard  set  for  lathe  and  their  names . 208 

,  box 200-201 

,  changing  height  changes  rake 220-221 

for  brass 211-212 

turret-lathes 200-207 

,  gang-planer.  .' 214-215 

,  grinder  for 468 

,  multiple-edge 217-218 

,  planer 211-215,  376 

,  ,  with  angular  adjustment 214 

,  rake  and  clearance  of  lathe 219-222 

,  slotting-machine 391 

,  spring,  for  lathe-work 219 

,  turret-forming 205 

,  uses  of  various  lathe 210-211 

Translating-gear,  use  of,  in  thread-cutting 282 

Turning  angular  face  of  bevel-gear  without  compound  rest 261 

curved  shapes 273-277 

Turret-machines,  a  plain  screw-machine 178-179 

,  automatic  screw-machine 182-183 

,  distinguishing  features 178 

,  flat  turret-lathe 186-191 

,  automatic  chuck  and  roller  feed 190-191 

,  cross-slide 190 

,  die-carriage 191 

,  examples  of  work  done  on  the  improved  ma- 
chine     198 

,  improved  design 191-198 

,  taper-turner  and  former 207 

,  Gisholt  chucking-lathe 183-185 

,  hollow  hexagon  lathe 185-186 

,  monitor  lathe 183 

,  tools  for 200-207 

,  work  done  with  forming-tools 205 

Turrets  used  on  engine-lathes 198-199 

Universal  back-rest  for  grinding-machine 480 

boring-machine 340 

chucks.  .  .  .    239 


554  INDEX 

PAGE 

Universal  dividers 5-6 

grinding-machine  and  work 471,  473-484 

radial  drill 94-95 

V  blocks 107,  374,  413,  416,  418 

V's,  drawn  tool-steel  for  lathes 174 

V  threads 294 

Valve  and  joint  grinding 507 

Valve-chucks 242 

Variable-speed  shaper-gear 368 

Vertical  boring-  and  turning-mills,  examples  of  work 343,  344,  352,  353 

miller 405,  418 

Vernier  calipers 8 

graduations  on  micrometer  calipers 10 

Vise,  combination  pipe 70 

for  taper  work  (swivel  jaw) 69 

,  quick-acting 70 

,  shaper  and  planer * 372-373 

,  solid  box 68 

,  universal 71 

Vise-clamps  and  mold  for  making  lead  clamps 72 

Vise-jaws  with  detachable  faces 71 

Vises,  hand  and  pin 71 

,  height  of 50 

,  holding  screws  in 72-73 

,  milling-machine 420-421 

parallel  and  parallel -swivel. 69 

Water-anneal 304 

Weight  of  castings  in  relation  to  pattern 520 

cubic  inch  of  various  metals 520 

Work,  protecting  finished 106,  234-235 

,  pins  for  holding  shaper  and  planer 373 

Worm,  cutting  left-hand 287 

Worm-wheel,  construction  of  dividing 458 

Worm-wheels 445 

Yard,  the,  its  value  defined  by  Congress  in  metres 2 

,  the  British  Imperial 1 

Yard-stick,  composition  of 1 

superseded  by  National  Prototype  Metre '.  . . .  2 

Zero  position  of  cutter  in  milling  gear-teeth 442 

dial-pointer  in  milling  gear-teeth 442 


^T        OF  THE 

UNIVERSITY 

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Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

Craig's  Azimuth 4*0,  3  50 

Doolittle's  Treatise  on  Practical  Astronomy ,.  .8vo,  4  oo 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy 8vo,  3  oo 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy i2mo,  2  oo 

BOTANY. 

Davenport's  Statistical  Methods,  with  Special  Reference  to  Biological  Variation. 

i6mo,  morocco,  i  23 

Thome'  and  Bennett's  Structural  and  Physiological  Botany i6mo,  2  25 

Westermaier's  Compendium  of  General  Botany.     (Schneider.) 8vo,  2  oo 

CHEMISTRY. 

Adriance's  Laboratory  Calculations  and  Specific  Gravity  Tables I2mo,  i   25 

Allen's  Tables  for  Iron  Analysis 8vo,  3  oo 

Arnold's  Compendium  of  Chemistry.     (Mandel.) Small  8vo,  3  50 

Austen's  Notes  for  Chemical  Students i2mo,  i  50 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Bolton's  Quantitative  Analysis 8vo,  i  50 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.    (Boltwood.).  .8vo,  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

Crafts's  Short  Course  in  Qualitative  Chemical  Analysis.   (Schaeffer.). .  .i2mo,  i  50 
Dolezalek's  Theory  of  the   Lead  Accumulator   (Storage  Battery).        (Von 

Ende.) i2mo,  2  50 

Drechsel's  Chemical  Reactions.     (Merrill.) I2mo,  i  25 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Erdmann's  Introduction  to  Chemical  Preparations.     (Dunlap.) izmo,  i  25 

3 


Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

i2mo,  morocco,  i  50 

Fowler's  Sewage  Works  Analyses i2mo,  2  09 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells.) 8vo,    5  ot 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.  (Wells.)  8vo,  3  o» 
System   of    Instruction    in    Quantitative    Chemical   Analysis.      (Cohn.) 

2  vols 8vo,  12  50 

Fuertes's  Water  and  Public  Health i2mo,  i  sc 

Furman's  Manual  of  Practical  Assaying 8vo ,  3  oc 

*  Getman's  Exercises  in  Physical  Chemistry i2mo,  2  oc 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) i2mo,  2  oo 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,  4  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan.) i2mo,  i  50 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  sc 

Hind's  Inorganic  Chemistry 8vo,  3  oc 

*  Laboratory  Manual  for  Students i2mo,  75 

Holleman's  Text-book  of  Inorganic  Chemistry.     (Cooper.) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,  2  50 

*  Laboratory  Manual  of  Organic  Chemistry.     (Walker.) i2mo,  i  oo 

Hopkins' s  Oil-chemists'  Handbook 8vo,  3  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  i  25 

Keep's  Cast  Iron 8vo,  2  50 

Ladd's  Manual  of  Quantitative  Chemical  Analysis i2mo,  i  oo 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  oo 

*  Langworthy  and   Austen.        The   Occurrence   of  Aluminium  in  Vege  able 

Products,  Animal  Products,  and  Natural  Waters 8vo,  2  oo 

Lassar-Cohn's  Practical  Urinary  Analysis.  (Lorenz.) i2mo,  i  oo 

Application  of  Some  General  Reactions  to  Investigations  in  Organic 

Chemistry.  (Tingle.) i2mo,  i  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz. ).i2mo,  i  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments.  ..  .8vo,  3  oo 

Lunge's  Techno-chemical  Analysis.  (Cohn.) i2mo,  i  oo 

Mandel's  Handbook  for  Bio-chemical  Laboratory i2mo,  i  50 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe .  .  i2mo,  60 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

3d  Edition,  Rewritten 8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  i  25 

Matthew's  The  Textile  Fibres 8vo,  3  50 

Meyer's  Determination  of  Radicles  in  Carbon  Compounds.     (Tingle.).  .  i2mo, 

Miller's  Manual  of  Assaying i2mo, 

Mixter's  Elementary  Text-book  of  Chemistry i2mo, 

Morgan's  Outline  of  Theory  of  Solution  and  its  Results i2ino, 

Elements  of  Physical  Chemistry i2mo, 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco, 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

Vol.  I Large  8vo,  5  oo 

O'Brine's  Laboratory  Guide  in  Chemical  Analysis 8vo,  2  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ostwald's  Conversations  on  Chemistry.     Part  One.     (Ramsey.) 12 mo,  i  50 

Ostwald's  Conversations  on  Chemistry.     Part  Two.     (Turnbull.).     (In  Press.) 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 

Pictet's  The  Alkaloids  and  their  Chemical  Constitution.     (Biddle.) 8vo,  5  oo 

Pinner's  Introduction  to  Organic  Chemistry.     (Austen.) i2mo,  i  50 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo,  i  25 

4 


*  Reisig's  Guide  to  Piece-dyeing.  .  .      8vo,  25  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Standpoint  8vo,  2  oo 

Richards's  Cost  of  Living  as  Modified  by  Sanitary  Science i2mo,  i  oo 

Cost  of  Food,  a  Study  in  Dietaries i2mo,  i  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Ricketts  and  Russell's  Skeleton  Notes  upon  inorganic  Chemistry.     (Part  I. 

Non-metallic  Elements.) 8vo,  morocco,  75 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Rideal's  Sewage  and  the  Bacterial  Purificat'on  of  Sewage 8vo,  3  50 

Disinfection  and  the  Preservation  of  Food 8vo,  4  oo 

Rigg's  Elementary  Manual  for'the  Chemical  Laboratory 8vo,  i  25 

Rostoski's  Serum  Diagnosis.  (Bolduan.) i2mo,  i  oo 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.  (Orndorff.) 8vo,  2  50 

Schimpf's  Text-book  of  Volumetric  Analysis I2mo,  2  50 

Essentials  of  Volumetric  Analysis i2mo,  i  25 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  mcrccco,  3  oo 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.  .  i6mo,  morocco,  2  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

:'f      Descriptive  General  Chemistry 8vo,  3  oo 

Treadwell's  Qualitative  Analysis.     (Hall.) 8vo.  3  oo 

Quantitative  Analysis.     (Hall.) 8vo,  4  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) I2iro,  i  50 

*  Walke's  Lectures  on  Explosives. 8vo,  4  oo 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

Wassermann's  Immune  Sera :  Haemolysins,  Cytotoxins,  and  Precipitins.    (Bol- 
duan.)   i2mo,  i  oo 

Well's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Text-book  of  Chemical  Arithmetic.     (In  press.) 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  5° 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process I2mo,  i  50 

Wulling's    Elementary    Course    in  Inorganic,  Pharmaceutical,  and  Medical 

Chemistry I2mo,  2  oo 

CIVIL  ENGINEERING. 

BRIDGES    AND    ROOFS.       HYDRAULICS.       MATERIALS   OF    ENGINEERING. 
RAILWAY  ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments i2mo,  3  oo 

Bixby's  Graphical  Computing  Table Paper  10^X24!  inches.  25 

**  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal.     (Postage, 

27  cents  additional.) 8vo,  3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

Davis's  Elevation  and  Stadia  Tables 8vo,  i  oo 

Elliott's  Engineering  for  Land  Drainage i2mo,  i  50 

Practical  Farm  Drainage i2mo,  i  oo 

Fiebeger's  Treatise  on  Civil  Engineering.     (In  press.) 

Folwell's  Sewerage.     (Designing  and  Maintenance.  1 8vo,  3  oo 

Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements I2rro,  i  75 

Goodrich's  Economic  Disposal  of  Towns'  Refuse 8vo,  3  50 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronorry &vo,  3  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors') i6mo,  morocco  2  50 

5 


Howe's  Retaining  Walls  for  Earth i2mo,  i  25 

Johnson's  (J.  B.)  Theory  and  Practice  of  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Laplace's  Philosophical  Essay  on  Probabilities.    (Truscott  and  Emory.) .  12010,  2  oo 

Mahan's  Treatise  on  Civil  Engineering.     (1873.)     (Wood.) 8vo,  5  oo 

*  Descriptive  Geometry 8vo,  i  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Elements  of  Sanitary  Engineering 8vo,  2  oo 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  morocco,  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Design i2mo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

8vo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

*  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

i6mo,  morocco,  i  25 

*  Wheeler  s  Elementary  Course  of  Civil  Engineering 8vo,  4  oo 

Wilson's  Topographic  Surveying 8vo,  3  50 

BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

*  Thames  River  Bridge 4to,  paper,  5  oo 

Burr's  Course  on  the  Stresses  in  Bridges  and  Roof  Trusses,  Arched  Ribs,  and 

Suspension  Bridges 8vo,  3  50 

Burr  and  Falk's  Influence  Lines  for  Bridge  and  Roof  Computations.  .  .  .  8vo,  3  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Greene's  Roof  Trusses » 8vo,  i  25 

Bridge  Trusses 8vo,  2  50 

Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Howe's  Treatise  on  Arches 8vo,  4  oo 

Design  of  Cimple  Roof-trusses  i«  Wood  and  Steel 8vo,  2  oo 

Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

Merriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I.     Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II.     Graphic  Statics 8vo,  2  50 

Part  HI.     Bridge  Design 8vo,  2  50 

Part  IV.     Higher  Structures 8vo,  2  50 

Morison's  Memphis  Bridge ^ 4to,  10  oo 

Waddell's  De  Pontibus,  a  Pocket-book  for  Bridge  Engineers.  .  i6mo,  morocco,  3  oo 

Specifications  for  Steel  Bridges i2mo,  i  25 

Wood's  Treatise  on  the  Theory  of  the  Construction  of  Bridges  and  Roofs .  .  8vo,  2  c > 
Wright's  Designing  of  Draw-spans: 

Part  I.     Plate-girder  Draws 8vo,  2  50 

Part  II.     Riveted-truss  and  Pin-connected  Long-span  Draws 8vo,  2  50 

Two  parts  in  one  volume 8vo,  3  50 

6 


HYDRAULICS. 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine.) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics v  . '. 8vo,  5  oo 

Church's  Mechanics  of  Engineering. .  •. 8vo,  6  oo 

Diagrams  of  Mean  Velocity  of  Wats*  in  Open  Channels payer,  i  50 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  OA 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works i2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Bering  and  Trau  vine.). 8vo  4  oo 

Hazen's  Filtration  of  Public  Water-supply 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water- works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  oo 

Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

8vo,  4  oo 

Merriman's  Treatise  on  Hydraulics 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Schuyler's   Reservoirs  for  Irrigation,   Water-power,  and   Domestic   Water- 
supply Large  8vo,  5  oo 

**  Thomas  and  Watt's  Improvement  of  Rivers.     (Post,  440.  additional. ).4to,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams 4to,  5  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Wilson's  Irrigation  Engineering Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines , 8vo,  2  50 

Elements  of  Analytical  Mechanics , , 8vo,  3  oo 

MATERIALS  OF  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction « - ,  . .  8vo,  5  oo 

Roads  and  Pavements '. .   3vo,  5  oo 

Black's  United  States  Public  Works Oblong  4to>  5  oo 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  go 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  5Q 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.     VoL  I Small  4to,  7  50 

Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Fowler's  Ordinary  Foundations * 8vo,  3  50 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Marten's  Handbook  on  Testing  Materials.     (Henning.)     2  vols 8vo,  7  50 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials 12 mo,  i  oo 

iietcalf's  Steel.     A  Manual  for  Steel-users 12 mo,  2  oo 

Patton's  Practical  Treatise  on  Foundations .. 8vo,  5  oo 

Richardson's  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction lomo,  mor.,  4  oo 

Rockwell's  Roads  and  Pavements  in  France i2ino,  i  25 

7 


Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Text-book  on  Roads  and  Pavements I2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     3  Parts 8vo,  8  oo 

Part  I.     Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II.     Iron  and  Steel 8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Thurston's  Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Waddell's  De  Pontibus.    ( A  Pocket-book  for  Bridge  Engineers.).  .  i6mo,  mor.,  3  oo 

Specifications  for  Stc.  1  Bridges i2mo,  i  25 

Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on* 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 

RAILWAY  ENGINEERING. 

Andrew's  Handbook  for  Street  Railway  Engineers 3x5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brook's  Handbook  of  Street  Railroad  Location i6mo,  morocco,  i  50 

Butt's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .i6mo,  morocco,  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:   (1879) Paper,  5  oo 

*  Drinker's  Tunnelling,  Explosive  Compounds,  and  Rock  Drills. 4to,  half  mor.,  25  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  i6mo,  mor.,  2  50 

Howard's  Transition  Curve  Field-book i6mo,  morocco,  i  50 

Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  i  oo 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  morocco,  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  Spiral i6mo,  morocco,  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  of  Calculating  the  Cube  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oo 

The  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

-,        I2mo,  morocco,  2  50 

Cross-section  Sheet Paper,  25 

Webb's  Railroad  Construction i6mo,  morocco,  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                                         "        Abridged  Ed 8vo,  i  50 

Coolidge's  Manual  of  Drawing 8vo,  paper  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  Oblong  4to,  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo.  2  50 

8 


Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts. 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry. 8vo,  3  oo 

Kinematics ;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting. 8vo,  i  50 

Industrial  Drawing.     (Thompson.) 8vo,  3  50 

Moyer's  Descriptive  Geometry 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design .  8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing.  i2mo,  oo 

25 


Drafting  Instruments  and  Operations 

Manual  of  Elementary  Projection  Drawing i2mo, 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 
Shadow i2mo, 


Plane  Problems  in  Elementary  Geometry I2tno, 

Primary  Geometry I2mo,  75 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry 8vo,  2  50 

Weisbach's  Kinematics  and  Power  of  Transmission.    (Hermann  and  Klein)8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Ait  of  Letter  Engraving i2mo,  2  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Perspective 8vo,  2  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 


ELECTRICITY  AND  PHYSICS. 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements. . . .  i2mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  CelL 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).8vo,  3  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  i6mo,  morocco,  5  oo 
Dolezalek's   Theory   of   the    Lead   Accumulator    (Storage    Battery).      (Von 

Ende.) i2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay.) 8vo,  a  50 

Hanchett's  Alternating  Currents  Explained I2mo,  I  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and   Tests Large  8 vo,  75 

Kinzbrunner's  Testing  of  Continuous-Current  Machines.  . 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  oo 

Le  Chatelien's  High-temperature  Measurements.  (Boudouard — Burgess.)  12010,  3  oo 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz.)  12 mo,  i  oo 


•*  Lyons's  Treatise  on  Electromagnetic  Phenomena.   Vols.  I.  and  II.  8vo,  each,  6  oo 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Ifiaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback.) i2mo, 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner.).  .  .8vo, 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo, 

Thurston's  Stationary  Steam-engines 8vo, 

*  Tillman's  Elementary  Lessons  in  Heat 8vo, 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo, 

Ulke's  Modern  Electrolytic  Copper  Refining „ 8vo,  3  oo 

LAW. 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

*  Sheep,  7  50 

Manual  for  Courts-martial. i6mo,  morocco,  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law I2mo,  2  50 

MANUFACTURES. 

Bernadou's  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Holland's  Iron  Founder I2mo,  2  50 

"  The  Iron  Founder,"  Supplement I2mo,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used  in  the 

Practice  of  Moulding I2mo,  3  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Fitzgerald's  Boston  Machinist i2mo,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Hopkin's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control Large  8vo,  7  50 

Matthews's  The  Textile  Fibres 8vo,  3  50 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Metcalfe's  Cost  of  Manufactures — And  the  Administration  of  Workshops. 8vo,  5  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Spalding's  Hydraulic  Cement i2tno,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses.    ...  i6mo,  morocco,  3  on 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.  .  i6mo,  morocco,  -j,  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,  5  oo 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Ware's  Manufacture  of  Sugar.     (In  press.) 

West's  American  Foundry  Practice I2mo,  2  50 

Moulder's  Text-book nmo,  2  50 

10 


Wolff's  Windmill  as  a  Prime  Mover 8vo,    3  oo 

Wood's  Rustless  Coatings:   Corrosion  and  Electrolysis  of  Iron  and  Steel.  .8vo,    4  oo 


50 

00 
»00 

50 

50 
50 
25 
50 
75 
50 
75 


MATHEMATICS. 

Baker's  Elliptic  Functions 8vo, 

*  Bass's  Elements  of  Differential  Calculus I2mo, 

Briggs's  Elements  of  Plane  Analytic  Geometry 12010, 

Compton's  Manual  of  Logarithmic  Computations i2tno, 

Davis's  Introduction  to  the  Logic  of  Algebra 8vo, 

*  Dickson's  College  Algebra Large  i2mo, 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  i2mo, 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo, 

Halsted's  Elements  of  Geometry 8vo, 

Elementary  Synthetic  Geometry , 8vo, 

Rational  Geometry i2mo, 

*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:   Vest-pocket  size. paper,         15 

100  copies  for    5  oo 

*  Mounted  on  heavy  cardboard,  8X10  inches,        25 

10  copies  for  2  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  Differential  Calculus.  .Small  8vo,  }  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  the  Integral  Calculus .  Small  8vo,  i  50 

Johnson's  (W.  W.)  Curve  Tracing  in  Cartesian  Co-ordinates i2mo,  i  oo 

Johnson's  (W.  W.)  Treatise  on  Ordinary  and  Partial  Differential  Equations. 

Small  8vo,  3  50 

Johnson's  (W.  W.)  Theory  of  Errors  and  the  Method  of  Least  Squares.  i2mo,  i  50 

*  Johnson's  (W.  W.)  Theoretical  Mechanics 1200,  3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.).  i2mo,  2  oo 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,  3  oo 

Trigonometry  and  Tables  published  separately -.  .Each,  2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  i  oo 

Maurer's  Technical  Mechanics &»-»  4  oo 

Merriman  and  Woodward's  Higher  Mathematics. 8vo,  5  oo 

Merriman's  Method  of  Least  Squares 8vo,  2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus. .  Sm.  8vo,  3  oo 

Differential  and  Integral  Calculus.     2  vols.  in  one Small  8vo,    2  50 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,    2  oo 

Trigonometry:  Analytical,  Plane,  and  Spherical i2mo,    i  oo 


MECHANICAL  ENGINEERING. 

MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Bacon's  Forge  Practice i2mo,  i  50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "  "  "        Abridged  Ed 8vo,     150 

Benjamin's  Wrinkles  and  Recipes i2mo,    2  oo 

Carpenter's  Experimental  Engineering 8vo,    6  oo 

Heating  and  Ventilating  Buildings 8vo,    4  oo 

Gary's  Smoke  Suppression  in  Plants  using  Bituminous  Coal.     (In  Prepara- 
tion.) 

Clerk's  Gas  and  Oil  Engine Small  8vo,    4  oo 

Coolidge's  Manual  of  Drawing 8vo,  paper,     i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,    2  50 

11 


Church's  Notes  and  Examples  in  Mechanics 8vo,  2  oo 

Compton's  First  Lessons  in  Metal- working i2mo,  50 

Compton  and  De  Groodt's  The  Speed  Lathe i2mo,  50 

Cromwell's  Treatise  on  Toothed  Gearing i2mo,  50 

Treatise  on  Belts  and  Pulleys i2mo,  50 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .i2mo,  50 

Dingey's  Machinery  Pattern  Making i2mo,  2  oo 

Dredge's  Record  of  the   Transportation  Exhibits  Building  of  the   World's 

Columbian  Exposition  of  1893 4to  half  morocco,  5*00 

Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.     I.     Kinematics 8vo,  3  50 

Vol.    II.     Statics 8vo,  4  oo 

Vol.  III.     Kinetics 8vo,  3  50 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

Vol.  II Small  4to,  10  oo 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i6mo,  i  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Rope  Driving i2mo,  2  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Hall's  Car  Lubrication i2mo,  i  oo 

Holly's  Art  of  Saw  Filing i8mo,  75 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle.  Sm.8vo,2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics i2mo,  3  oo 

Johnson's  (L.  J.)  Statics  by  Graphic  and  Algebraic  Methods 8vo,  2  oo 

Jones's  Machine  Design : 

Part   L     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

Leonard's  Machine  Shop,  Tools,  and  Methods.     (In  press.) 

lorenz's  Modern  Refrigerating  Machinery.      (Pope,  Haven,  and  Dean.)      (In  press.) 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Velocity  Diagrams 8vo,  i  ^o 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

*  Elements  of  Mechanics i2mo,  i  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Reagan's  Locomotives:   Simple,  Compound,  and  Electric i2mo/  2  50 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.  8vo,  3  oo 

Richards's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     VoL  1 8vo,  2  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Sinclair's  Locomotive-engine  Running  and  Management i2tno,  2  oo 

Smith's  (O.)  Press-working  of  Metals 8vo,  3  oo 

Smith's  (A.  W.)  Materials  of  Machines I2mo,  1  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Treatise  on  Friction  and  Lost  "\7ork  in    Machinery  and    Mill 

Work 8vo(  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

i2mo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Weisbach's  Kinematics  and  Power  of  Transmission.    (Herrmann — Klein.).  8vo,  5  oo 

Machinery  of  Transmission  and  Governors.      (Herrmann — Klein.). 8vo,  5  oo 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Principles  of  Elementary  Mechanics 121:10,  i  25 

Turbines 8vo.  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

14 


METALLURGY. 

tfgleston's  Metallurgy  of  Silver,  Gold,  and  Mercury: 

Vol.    I.     Silver 8vo,  750 

Vol.  II.     Gold  and  Mercury f 8vo,  7  So 

**  Iles's  Lead-smelting.     (Postage  9  cents  additional.). . . , I2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe.' 8vo,  i  50 

Le  Cttatelier's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo,  3  oo 

Metcalf  s  Steel.     A  Manual  for  Steel-users     , i2mo,  2  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts , 8vo,  8  oo 

Part   U.     Iron  and  Steel 8vo.  3  5° 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.    Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo  3  oo 

Map  of  Southwest  Virignia Pocket-book  form.  2  oo 

Brush's  Manual  of  Determinative  Mineralogy.     (Penn^ld.) 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals 8vo,  3  50 

Dana's  System  of  Mineralogy Large  8vo,  half  leather,  12  50 

First  Appendix  to  Dana's  New  "  System  of  Mineralogy." Large  8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them I2mo,  i  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography I2mo  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  i  oo 

Eafcle's  Mineral  Tables 8vo,  i  25 

Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  2  50 

Hussak's  The  Determination  of  Rock-forming  Minerals.    (Smith. ).  Small  8vo,  2  oo 

Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses 8vo,  4  oo 

*  P&nfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo   paper,  o  50 
Rosenbusch's   Microscopical   Physiography   of   the   Rock-making  Minerals. 

(Iddings.) ". 8vo.  5  oo 

*  Tollman's  Text-book  of  Important  Minerals  and  Rocks .8vo.  2  oo 

Williams's  Manual  of  Lithology 8vo,  3  oo 

MINING. 

Beard's  Ventilation  of  Mines I2mo.  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo.  3  oo 

M*,p  of  Southwest  Virginia Pocket  book  form.  2  oo 

Dougl&!»'s  Untechnical  Addresses  on  Technical  Subjects  .  . 12010.  i  oo 

*  Darter's  Tunneling,  Explosive  Compounds,  and  Rock  Drills.  .4to.hf.  mor  ,  25  oo 

Eissler'6  Modern  High  Explosives 8vo  4  oo 

Fowler's  Sewage  Works  Analyses I2mo  2  oo 

Goodyear's  Coal-mines  of  the  Western  Coast  of  the  United  States i2mo.  2  50 

Ihlseng's  Manual  of  Mining .8vo.  5  oo 

**  Iles's  Lead-smelting.     (Postage  gc.  additional.) I2mo.  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe,  . .8vo.  i  50 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo.  2  oo 

*  Walke's  Lectures  on  Explosives 8vo,    4  oo 

Wilson's  Cyanide  Processes I2mo,     i  50 

Chlcr'jiation  Process xamo,    i  50 

15 


Wilson's  HydrauLv  and  .Placer  Mining i2mo,  2  oe 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation t2mo',  i  25 

SANITARY  SCIENCE. 

FolwelTs  Sewerage.     (Designing,  Construction,  and  Maintenance.) 8vo,  3  oc 

Water-supply  Engineering gvo,  4  oo 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works '  '  '  I2mo,  2  50 

"Gerhard's  Guide  to  Sanitary  House-inspection i6mo,  i  oo 

Goodrich's  Economic  Disposal  of  Town's  Refuse Demy  8vo,  3  50 

Hazen's  Filtration  of  Public  Water-supplies 8vo,  3  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Mason's  Water-supply.  (Considered  principally  from  a  Sanitary  Standpoint)  8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  i  25 

Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  oo 

Ogden's  Sewer  Design i2mo,  2  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis I2mo,  i  25 

*  Price's  Handbook  on  Sanitation i2mo,  i  50 

Richards's  Cost  of  Food.     A  Study  in  Dietaries i2mo,  i  oo 

Cost  of  Living  as  Modified  by  Sanitaiy  Science i2mo,  i  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point     8vo,  2  oo 

*  Richards  and  Williams's  The  Dietary  Computer '. 8vo,  i  50 

Rideal's  Sewage  and  Bacterial  Purification  of  Sewage 8vo,  3  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo,  i  oo 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Woodhull's  Notes  on  Military  Hygiene 16100,  i  50 

MISCELLANEOUS. 

De  Fursac's  Manual  of  Psychiatry.  (Rosanoff  and  Collins.).  .  .  .Large  I2mo,  2  50 
Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

Ferrel's  Popular  Treatise  on  the  Winds Svot  4  oo 

Haines's  American  Railway  Management i2mo,  2  50 

Mott's  Composition,  Digestibility,  and  Nutritive  Value  of  Food.  Mounted  chart,  i  25 

Fallacy  of  the  Present  Theory  of  Sound i6mo,  i  oo 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.  .Small  8vo,  3  oo 

Rostoski's  Serum  Diagnosis.  (Bolduan.) i2mo,  i  oo 

Rotherham's  Emphasized  New  Testament Large  8vo,  2  oo 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

Totten's  Important  Question  in  Metrology 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

Von  Behring's  Suppression  of  Tuberculosis.  (Bolduan.) i2mo,  i  oo 

Winslow's  Elements  of  Applied  Microscopy I2mo,  i  50 

Worcester  and  Atkinson.  Small  Hospitals,  Establishment  and  Maintenance; 

Suggestions  for  Hospital  Architecture:  Plans  for  Small  Hospital.  i2mo,  i  25 

HEBREW  AND   CHALDEE  TEXT-BOOKS. 

Green's  Elementary  Hebrew  Grammar I2mo,  i  25 

Hebrew  Chrestomathy 8vo,  2  oo 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to   the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  morocco,  5  oo 

Lettews's  Hebrew  Bible 8vo,  2  25 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
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